SHELF LIFE OF FIVE MEAT PRODUCTS DISPLAYED UNDER LIGHT EMITTING DIODE OR FLUORESCENT LIGHTING KYLE STOVER STEELE. B.S., Kansas State University, 2009

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1 SHELF LIFE OF FIVE MEAT PRODUCTS DISPLAYED UNDER LIGHT EMITTING DIODE OR FLUORESCENT LIGHTING by KYLE STOVER STEELE B.S., Knss Stte University, 2009 A THESIS Submitted in prtil fulfillment of the requirements for the degree MASTER OF SCIENCE Deprtment of Animl Sciences & Industry College of Agriculture KANSAS STATE UNIVERSITY Mnhttn, Knss 2011 Approved by: Mjor Professor Elizbeth A. E. Boyle

2 Copyright KYLE STOVER STEELE 2011

3 Abstrct Light emitting diode (LED) nd fluorescent (FLS) lighting effects on enhnced pork loin chops, beef longissimus dorsi nd semimembrnosus steks, ground beef, nd ground turkey displyed in two retil disply cses set up with similr opertionl tempertures were evluted using visul nd instrumentl color, Enterobctericee (EB) nd erobic plte counts (APC), internl product nd cse tempertures, nd thiobrbituric cid rective substnces (TBARS). Visul discolortion of the five met products incresed (P<0.05) s disply time incresed. Beef longissimus dorsi steks, ground beef, nd the superficil portion of beef semimembrnosus steks hd less (P<0.05) visul discolortion under LED lighting thn FLS. Compred to FLS, pork loin chops under LED lighting hd higher (P<0.05) L* vlues nd lower (P<0.05) /b rtio. The deep portion semimembrnosus stek under LED ws redder (P<0.05) nd the superficil portion hd lower (P<0.05) /b rtio; LED deep nd superficil portion semimembrnosus steks hd higher (P<0.05) sturtion index vlues t 5.18 nd 4.47, respectively, on d 0 thn FLS. Pork chops under LED lighting hd lower (P<0.05) APC popultions thn FLS by the end of disply. Enterobctericee popultions fluctuted throughout disply on ground turkey under FLS lighting while popultions remined stble under LED. APC popultions incresed s disply time incresed for pork loin chops, ground beef nd ground turkey, but not beef longissimus dorsi steks possibly due to initil cse-redy postmortem ge. As disply time incresed, EB popultions incresed (P<0.05) for pork loin chops, ground beef nd ground turkey. The internl temperture of ll products, except beef longissimus dorsi steks, ws lower (P<0.05) in the LED cse. FLS cse tempertures were higher (P<0.05) by 0.56 to 1.11 C thn LED over the durtion of the study. Pork loin chops, ground turkey, nd beef semimembrnosus steks hd higher (P<0.05) TBARS vlues by 0.06 to 0.24 mg mlonldehyde/kg under LED lighting, but lighting type did not ffect (P>0.05) lipid oxidtion of beef longissimus dorsi steks or ground beef. LED lighting results in lower disply cse tempertures, lower internl product tempertures, nd extended color life; however, lipid oxidtion ws incresed in some cuts under LED lighting.

4 Tble of Contents List of Figures... vii List of Tbles... xii Acknowledgements... xiv CHAPTER 1 - Impct of Disply Lighting on the Color Stbility nd Shelf Life of Five Fresh Met Products... 1 CHAPTER 2 - Review of Literture... 4 Effect of Met Color on Purchsing Decisions... 4 Economics of Met Color... 4 Myoglobin Chemistry... 5 Sttes of Myoglobin... 5 Metmyoglobin Reducing Activity... 6 Oxygen Consumption Rte... 7 Fctors Affecting Discolortion of Met... 7 Intrinsic Fctors... 8 Extrinsic Fctors... 8 Temperture...8 Grinding...9 Bcteril Contmintion...9 Chilling Rte...10 Oxygen Pressure...10 Lipid Oxidtion...11 Pckging Polyvinyl Chloride Pckging Modified Atmosphere Pckging Retil Disply Lighting Effect on Met Shelf Life Lighting Effect on Odor Lighting Effect on Microbil Popultions Lighting Effect on Lipid Oxidtion Lighting Effect on Color iv

5 LED Lighting Reltionship Between Visul nd Instrumentl Color Visul Color Evlution Instrumentl Color Anlysis Reltionship of Visul nd Instrumentl Color CHAPTER 3 - Shelf Life of Five Met Products Displyed Under Light Emitting Diode or Fluorescent Lighting Abstrct Introduction Mterils nd Methods Retil Disply Cses Disply Lighting Cse Tempertures Rw Mterils nd Pckging for Disply Initil ph Visul Color Instrumentl Color Product Internl Temperture Gs Concentrtion Odor TBARS Microbiology Sttisticl Anlysis Results nd Discussion Initil Conditions Cse Tempertures nd Cycling Visul Color Evlution Instrumentl Color Mesurements Product Internl Temperture Odor Lipid Oxidtion TBARS v

6 Product Microbiology CHAPTER 4 - Conclusions References Appendix A - Figures nd Tbles Figures nd Tbles Within Appendices Appendix B - Cse Specifictions nd Visul Color Anlysis Appendix C - Sttisticl Codes Product ph Cse Tempertures Visul Color Instrumentl L* Color Instrumentl * Color Instrumentl b* Color Instrumentl Sturtion Index Instrumentl /b Rtio Instrumentl Hue Angle Product Internl Tempertures Odor Lipid Oxidtion-TBARS Product Microbiology Appendix D - Visul Color Scles vi

7 List of Figures Fig Myoglobin pigment in the different sttes of existence (From Mncini & Hunt, 2005). 6 Fig I-button temperture logger loctions in fluorescent (FLS) nd light emitting diode (LED) disply cses Fig Lest squres mens (Lsmens) for cse temperture pooled from 30 loctions in refrigerted disply cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for cse temperture 1 t six shelf loctions in refrigerted disply cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for visul color of five products 1 displyed in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for visul color 1 of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig. 3-6 Lest squres mens (Lsmens) for visul color 1 of beef longissimus dorsi steks over 2 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for visul color 1 of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for visul color 1 of ground turkey over 7 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for visul color 1 of beef semimembrnosus deep portion steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting vii

8 Fig Lest squres mens (Lsmens) for visul color 1 of beef semimembrnosus superficil portion steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for L* 1, * 2 nd b* 3 instrumentl color vlues of five products displyed in refrigerted cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for sturtion index 1, /b rtio 2 nd hue ngle 3 instrumentl color of five products displyed in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for internl temperture of five products 1 displyed in refrigerted cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting.46 Fig Lest squres mens (Lsmens) for internl temperture of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for internl temperture of ground turkey over 7 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for internl temperture of beef semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for subjective odor of five products 1 displyed in refrigerted cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for oxidtive rncidity (TBARS) of five products 1 displyed in refrigerted cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for oxidtive rncidity (TBARS) of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting viii

9 Fig Lest squres mens (Lsmens) for oxidtive rncidity (TBARS) of beef longissimus dorsi steks over 2 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for oxidtive rncidity (TBARS) of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for oxidtive rncidity (TBARS) of ground turkey over 7 dys of refrigerted in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for oxidtive rncidity (TBARS) of beef semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Men popultions for erobic plte count (APC) nd Enterobctericee (EB) popultions cross three smpling periods 1 for five products 2 during refrigerted retil disply 3 in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. 53 Fig Lest squres mens (Lsmens) for erobic plte count (APC) 1 nd Enterobctericee (EB) 2 popultions cross three smpling periods for five products 3 during refrigerted retil disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for L* 1, * 2, & b* 3 instrumentl color vlues of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for sturtion index 1, /b rtio 2, & hue ngle 3 instrumentl color of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for L* 1, * 2, & b* 3 instrumentl color vlues of beef longissimus dorsi steks over 2 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for sturtion index 1, /b rtio 2, & hue ngle 3 instrumentl color of beef longissimus dorsi steks over 2 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting ix

10 Fig Lest squres mens (Lsmens) for L* 1, * 2, & b* 3 instrumentl color vlues of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for sturtion index 1, /b rtio 2, & hue ngle 3 instrumentl color of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for L* 1, * 2, & b* 3 instrumentl color vlues of ground turkey over 7 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for sturtion index 1, /b rtio 2, & hue ngle 3 instrumentl color of ground turkey over 7 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for L* 1 & * 2 instrumentl color vlues of beef semimembrnosus deep portion steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for L* 1 instrumentl color vlues of beef semimembrnosus superficil portion steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for /b rtio 1 & hue ngle 2 instrumentl color of beef semimembrnosus superficil portion steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for internl temperture of beef longissimus dorsi steks over 2 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for internl temperture of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Lest squres mens (Lsmens) for Aerobic Plte Count (APC) popultions of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting x

11 Fig Lest squres mens (Lsmens) for Aerobic Plte Count (APC) popultions of beef longissimus dorsi steks over 2 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for Aerobic Plte Count (APC) popultions of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for Aerobic Plte Count (APC) popultions of ground turkey over 7 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for Enterobctericee (EB) popultions of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Fig Lest squres mens (Lsmens) for Enterobctericee (EB) popultions of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting UV, correlted color tempertures nd lumens for fluorescent (FLS) nd light emitting diode (LED) lighting Fig Five fresh met products displyed in retil disply cses outfitted with fluorescent or light emitting diode lighting. (Photo courtesy of Dr. Melvin Hunt) Fig Product lyout within ech disply cse Fig Superficil nd deep portion of the beef semimembrnosus xi

12 List of Tbles Tble 1. Probbility vlues for lighting type, dy of disply, nd lighting type by dy of disply interctions for visul nd L*, * nd b* instrumentl color Tble 2. Probbility vlues for lighting type, dy of disply, nd lighting type by dy of disply interctions for sturtion index, /b rtio nd hue ngle Tble 3. Probbility vlues for lighting type, dy of disply, nd lighting type by dy of disply interctions for thiobrbituric cid rective substnces (TBARS), erobic plte counts nd enterobctericee counts Tble 4. Lest squres mens (Lsmens) for ph of five met products nd gs compositions of products received in mother bgs Tble 5. Gs composition of ground turkey pre-pckged in modified tmosphere during refrigerted disply under fluorescent (FLS) or light emitting diode (LED) lighting Tble 6. Disply cse condenser cycling nd run time during disply using fluorescent (FLS) or light emitting diode (LED) lighting Tble 7. Lest squres mens (Lsmens) for * vlues of the superficil portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Tble 8. Lest squres mens (Lsmens) for b* vlues of the superficil portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Tble 9. Lest squres mens (Lsmens) for b* vlues of the deep portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Tble 10. Lest squres mens (Lsmens) for sturtion index vlues of the superficil portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Tble 11. Lest squres mens (Lsmens) for sturtion index vlues of the deep portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting xii

13 Tble 12. Lest squres mens (Lsmens) for /b rtio vlues of the deep portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Tble 13. Lest squres mens (Lsmens) for hue ngle vlues of the deep portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Tble 14. Lest squres mens (Lsmens) for Aerobic Plte Count (APC) popultions of pork loin chops in refrigerted disply cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Tble 15. Lest squres mens (Lsmens) for Enterobctericee (EB) popultions of beef longissimus dorsi steks in refrigerted disply cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Tble 16. Lest squres mens (Lsmens) for Enterobctericee (EB) popultions of ground turkey in refrigerted disply cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting xiii

14 Acknowledgements I would like to thnk my mjor dvisor, Dr. Elizbeth Boyle, for her guidnce, encourgement, nd support throughout my grdute experience. She ws bundntly helpful in focusing my ttention to minor detils in projects. Prepring for the professionl world hs been esy hving tlented mentor who is knowledgeble, personble, nd professionl. I gretly pprecite the ptience she exhibited throughout my mster s reserch. I extend pprecition to my committee, Drs. Melvin Hunt nd Fdi Armouni, for their encourgement nd guidnce throughout this mster s experience. I m fortunte to hve hd the opportunity to lern from these gret minds nd I look forwrd to pplying the knowledge to the met nd niml industry. A specil thnks goes to Dr. Dlls Johnson for his sttisticl expertise in setting up the study nd nlyzing results. I would like to show my grtitude to Hussmnn for supplying the disply cses nd finncil support of the project s well s Yoelit Hiebert, Joel Attey, nd Kren Abrolt for their commitment nd trust to Knss Stte University in crrying out their project. The time nd effort these individuls spent orgnizing nd specifying the project resulted in study tht will be very beneficil to the entire met industry. In ddition, I thnk Crgill for supplying the met products used in this study. The reltionship between Crgill nd the Knss Stte mets deprtment is invluble. I owe my deepest grtitude to Meliss Weber for the time nd effort she put into designing nd orgnizing this project. Her help with this project ws priceless. I pprecite the ptience she offered s I begn my involvement with the project. No Mster s project cn be crried out lone. Therefore, I m indebted to ll of the grdute students nd undergrdute workers who offered their time nd expertise in helping set up, crry out, nd record the experiment. It is gret plesure to be prt of Knss Stte University nd the Deprtment of Animl Sciences. The support in terms of fcilities, equipment, nd the ssistntship ws beyond generous. Without this support, I would hve chosen different pth in life. Finlly, I would like to thnk my fther, Jck, my mother, Crolyn, nd my brother, Kelly, for their support nd encourgement. They hve been n inexhustible resource my entire xiv

15 life. Without hesittion, their bcking ws constnt fctor I could len on throughout grdute school. I look forwrd to enjoying severl more fun-filled nd successful yers with my fmily. xv

16 CHAPTER 1 - Impct of Disply Lighting on the Color Stbility nd Shelf Life of Five Fresh Met Products Retil customers do not hve methods to estimte tenderness, juiciness or flvor when evluting met cuts for purchse. Insted, color is one of the mjor criteri in selecting met items (Kropf, 1993). During refrigerted disply, fresh met color chnges nd customers discriminte ginst discolored mets. Met items with discolortion must be discounted or discrded leding to revenue losses up to $1 billion for the met industry (Smith, Belk, Sofos, Ttum, & Willims, 2000). Myoglobin is the primry pigment responsible for met color. Pigment concentrtion nd the physicl prmeters of met, including light scttering nd bsorbing properties, ffect met color (Kropf, 1993). Myoglobin protein exists s deoxymyoglobin, oxymyoglobin, or metmyoglobin depending upon the stte of the iron molecule s well s the occuption of the sixth lignd. Oxymyoglobin presents bright red color to met nd possesses n oxygen molecule on the sixth lignd with the reduced form of iron (Fustmn & Cssens, 1990). Metmyoglobin is the pigment responsible for the undesirble brown color of met tht occurs when iron hs been oxidized nd wter occupies the sixth lignd (Fustmn & Cssens, 1990). Met color is the result of the interction of mny fctors (Kropf, 1993). Metmyoglobin formtion depends on the reducing bility unique to ech beef muscle (Ledwrd, Smith, Clrke, & Nicholson, 1977). Once met is plced in retil disply, physicl fctors begin to influence fresh met color. Lowering disply tempertures 3 to 5 C will retrd discolortion (McDougll & Tylor 1975). The vilbility of oxygen to bind with myoglobin ffects the rte of discolortion. Oxygen prtil pressure between mmhg is the optimum level promoting metmyoglobin formtion (George & Strtmn, 1952). Bcteril contmintion of met will ffect product color. Short loins inoculted with Pseudomons frgi were found to promote discolortion (Bl, Mrshll, Stringer, & Numnn 1977). Lipid oxidtion products promote metmyoglobin formtion which ws greter in study with oxymyoglobin treted with oxidized liposomes versus freshly prepred liposomes (Chn, Fustmn, & Decker, 1997). Diet (French, Stnton, Rwless, O Riordn, Monhn, Cffery, & Moloney 2000; Bublits, Brown, Pohlmn, Johnson, Onks, Lovedy, Morrow, Sndelin, Coblentz, Richrds, & Pugh 2004; Relini, Duckett, Brito, Dll Rizz, & De Mttos 2004), genetics, nd breed (Brewer, Jensen, Sosnicki, Fields, 1

17 Wilson, & McKeith, 2002; Brewer, Sosnicki, Fields, Hnkes, Ryn, Zhu, & McKeith, 2004) lso influence met color. These vribles must be well understood in order to contend with the complexity of met color. The met industry is wre of the mjor role lighting type nd intensity hs on the ppernce of met in retil disply. Lighting technology hs developed to extend fresh met color. A fluorescent (FLS) bulb housing n ultrviolet-filter plte of polycrbonte extended fresh pork susge disply life by 12 dys compred to stndrd supermrket FLS tube (Mrtínez, Cill, Antonio, & Ronclés, 2007). Newer technologies in lighting offer the bility to enhnce met color plus reduce other costly inputs for met retil disply. Light emitting diode (LED) lighting offers dvntges for disply by being more energy efficient nd hving reduced het genertion throughout disply. LED technology begn in the 1950 s with commercil production strting in the lte 1960 s (DOE, 2009). Currently, less thn n estimted 1 percent of the refrigerted disply cses hve LED lighting technology instlled (DOE, 2008). Phosphor converted LEDs hve higher efficcies compred to incndescent nd compct fluorescent light bulbs leding to significnt energy svings (Arik, 2009). The United Sttes Deprtment of Energy (DOE) relizes the potentil cost nd energy svings LED lighting holds due solely to efficiency. Gols hve been set by the United Sttes government for the fiscl yer 2015 to produce LED lighting systems costing less thn $2/klm with color-rendering index (CRI) greter thn 80, correlted color temperture (CCT) less thn 5000 K, nd 126 lm/w luminire tht emits pproximtely 1000 lumens (DOE, 2009). Currently, wrm white LED systems with CCT less thn 3300 K possess lm/w while compct fluorescent lighting possesses lm/w. Although both technologies possess similr efficcies, fluorescent technology is close to mxing out on efficcy while LED systems hold the potentil to improve two-fold on energy efficiency (DOE, 2009). In ddition, LED lighting provides longer operting life, lower mintennce nd life cycle costs, miniml light loss, directionl illumintion, djustble color, nd uniform illumintion (DOE, 2008). LED lighting will mke strong ppernce in retil disply met cses with potentil cost svings, energy svings, nd lower het genertion. Energy svings up to 2.1 TWh of electricity is possible if the entire refrigerted mrket converted to LED lighting (DOE, 2008). As LED lighting provides lower energy costs, longer operting life, nd lower operting 2

18 tempertures, reserch is needed to evlute how LED lighting ffects the color stbility nd shelf life of fresh met. The objective of this study ws to determine the effects of LED nd FLS lighting on visul nd instrumentl met color nd shelf-life properties of five types of fresh met products displyed in two retil disply cses running t similr temperture profiles. 3

19 CHAPTER 2 - Review of Literture Effect of Met Color on Purchsing Decisions Historiclly, the first encounter with refrigerted retil met cuts in self-service met cses ws with met products pckged on Styrofom trys nd overwrpped with polyvinyl chloride () plstic (McMillin, 2008). This pckging style llowed for oxygen to bind to the met pigment myoglobin resulting in process clled bloom, red color due to the formtion of oxymyoglobin. Consequently, consumers ssocited the bright red color with fresh nd wholesome met items (Jenkins & Herrington, 1991). Tody, consumers continue to use color s one of the mjor criteri in selecting met products (Kropf, 1993) s they do not hve methods to estimte tenderness, juiciness or flvor of pckged retil cuts on disply. Strong reltionships exist between the desired met color nd purchsing intent with consumer preference towrds red colored beef items (Crpenter, Cornforth, & Whittier, 2001). Consumers begin rejecting products for purchse once discolortion of the met in disply reches 20% (Kropf, 1993) to 40% (Greene, Hsin, & Zipser, 1971) discolortion. Bis towrds met products with the bloomed color hs not been linked to pltbility. Untrined pnelists evluted beef loin steks for rw color nd purchsing preference, long with cooked flvor, juiciness, nd tenderness (Crpenter et l., 2001). While pnelists observed significnt difference in color nd reported purchsing preferences for red colored steks, no differences existed in flvor, juiciness, or tenderness between the different colored steks (Crpenter et l., 2001). In n dditionl study, discolortion in retil disply beef steks ws considered uncceptble to the consumer (Jeremih, Crpenter, & Smith, 1972). However, the tste pnel indicted no reltionship between fresh met color nd cooked pltbility of the steks (Jeremih et l., 1972). Economics of Met Color Met color stbility is defined s the durtion of n cceptble, sleble color (Kropf, 1993). Shelf life of met products usully ends s result of discolortion insted of bcteril spoilge (Smith, Morgn, Sofos, Ttum, & Schmidt, 1995). Once met cut reches n uncceptble percentge discolortion the consumer will choose not to purchse the product. Eye 4

20 of round steks expressing more thn 40% discolortion were rejected for purchse by trined color pnel (Greene, et l., 1971). When discolortion ccumultes on met item, the product must be discounted, reprocessed into lower vlued item, or discrded. Therefore, ny met products with discolortion must be discounted or discrded leding to lrge revenue losses up to $1 billion for retilers (Smith, et l., 2000). Myoglobin Chemistry Sttes of Myoglobin Myoglobin is the min pigment responsible for met color (Fustmn & Cssens, 1990). Myoglobin consists of n iron molecule within heme ring in either the ferric (Fe 3+ ) or ferrous (Fe 2+ ) stte, nd protoporphyrin ring (Fustmn & Cssens, 1990). The concentrtion of myoglobin nd other pigments nd the physicl prmeters of met, including light scttering nd bsorbing properties, influence met color (Kropf, 1993). Myoglobin in fresh met exists s deoxymyoglobin, oxymyoglobin, or metmyoglobin depending upon the stte of the iron molecule s well s the occuption of the sixth lignd (Fig. 2-1). Deoxymyoglobin exhibits purple color with iron in the reduced stte with the sixth lignd vcnt (Fustmn & Cssens, 1990). Oxymyoglobin presents bright red met color nd possesses n oxygen molecule on the sixth lignd with the reduced form of iron (Fustmn & Cssens, 1990). Metmyoglobin is the pigment responsible for the undesirble brown color on met. Discolortion occurs when iron hs been oxidized nd wter occupies the sixth lignd (Fustmn & Cssens, 1990). The pigments in greter concentrtion will determine the color observed by consumers. Higher concentrtions of the oxymyoglobin pigment re the trget for processors nd retilers since this is the color preferred by consumers. 5

21 Fig Myoglobin pigment in the different sttes of existence (From Mncini & Hunt, 2005). O 2 = Oxygen, DMb= Deoxymyoglobin, Fe ++ =Ferrous iron, ATM= Atmospheric, OMb= Oxymyoglobin, O 2 pp=oxygen prtil pressure, MMb=Metmyoglobin, Fe +++ =Ferric iron, COMb= Crboxymyoglobin. Metmyoglobin Reducing Activity The dominnce of metmyoglobin s the pigment in met product depends upon severl fctors including the inherent reducing bility of met (Mncini & Hunt, 2005; Knner, 1994). Competition for dominnt pigment between oxymyoglobin nd metmyoglobin is regulted by metmyoglobin reduction ctivity (MRA) which is unique to ech muscle (Ledwrd et l., 1977). Metmyoglobin reduction ctivity is the enzymtic pthwy of reducing the iron molecule in metmyoglobin bck to the Fe 2+ stte in the presence of the coenzyme nicotinimide dinucleotide (NADH) (Renerre, 1990). The bility to reduce iron in metmyoglobin hs been reported to be more dependent on the vilbility of NADH thn MRA (Bekhit, Geesink, Ilin, Morton, & Bickerstffe, 2003). Lctte dehydrogense is n endogenous enzyme in beef tht replenishes the supply of NADH in lctte enhnced beef by converting the lctte into pyruvte nd NADH (Mncini, Hunt, Kim, & Lwrence, 2004). This replenished supply of NADH restores MRA nd increses color stbility. One study hs relted the loction of MRA ctivity to microsomes nd 6

22 intct mitochondri of muscles (Echevrne, Renerre, & Lbs, 1990). Slow-twitch muscle fibers possess greter potentil for hving more microsomes nd intct mitochondri thn fst-twitch muscle fibers. Additionl NADH my be produced from the reversl of the electron trnsport chin in mitochondri (Giddings, 1974). Once combintion of decresing ph, loss of substrtes or coenzymes, nd loss of functionl nd structurl integrity of mitochondri occurs, MRA ceses to function (Giddings, 1974). Oxygen Consumption Rte Myoglobin s role in muscle tissues is to trnsport oxygen to mitochondri in cells for energy production (Wittenberg & Wittenberg, 1975). When oxygen is ttched, myoglobin is in the oxymyoglobin form resulting in bright red pigment (Fustmn & Cssens, 1990). After oxygen hs been delivered to the mitochondri, myoglobin hs vcncy t the sixth lignd resulting in either deoxymyoglobin or oxidtion to the metmyoglobin pigment (Fustmn & Cssens, 1990). High oxygen consumption rte (OCR) by mitochondri in n open met system results in greter mounts of metmyoglobin formtion (Tng, Fustmn, Hoglnd, Mncini, Seyfert, & Hunt, 2005). With higher OCR, the oxygen surrounding the met will be used up nd myoglobin will be susceptible to becoming the brown metmyoglobin pigment through oxidtion (Lnri & Cssens, 1991). High OCR is detrimentl to the functionlity of the enzymic reducing system leding to utoxidtion of myoglobin (Ledwrd, 1985). Muscles with weker color stbility hve been linked with high mitochondril content up to 0.5 mg/ml t ph 5.6 (Tng et l., 2005) nd high oxygen uptke (Lnri & Cssens, 1991). Fster rtes of ph decline nd lower finl ph my inhibit the respirtory ctivity of mitochondri (Lnri & Cssens, 1991). Muscles with lower ph were found to hve lower OCR leding to improved color stbility (Lnri & Cssens, 1991; Tng et l., 2005). Oxygen consumption rte ws found to decrese over time (Tng et l., 2005) up to 48 h postmortem (Lnri & Cssens, 1991). Lnri nd Cssens (1991) concluded tht OCR hs greter impct on color stbility compred to MRA since smples with the wekest color stbility possessed the highest reducing ctivities. Fctors Affecting Discolortion of Met Met color is the result of the interction of mny fctors (Kropf, 1993), including intrinsic nd extrinsic fctors. Understnding the influence ech fctor hs upon met color long 7

23 with the reltionship to other prmeters will llow processors nd retilers to mximize color life of fresh met products. Intrinsic Fctors Breed nd genetics of n niml ffect fresh met color (Brewer et l., 2002, 2004). For exmple, Holstein cttle were found to hve greter OCR leding to weker color stbility in the longissimus dorsi nd gluteus medis steks compred to steks from crossbred cttle (Lnri & Cssens, 1991). Furthermore, they found color stbility to be muscle dependent with the longissimus dorsi hving greter color stbility compred to the gluteus medis. Supporting this conclusion is study by Fustmn nd Cssens (1991) who reported tht longissimus dorsi muscles ccumulted 9.2% less metmyoglobin thn gluteus medis muscles. Compred to fsttwitch glycolytic or fst-twitch oxidtive-glycolytic muscle fibers, slow-twitch oxidtive muscle fibers contin greter mount of myoglobin nd possess higher enzymic reducing ctivity resulting in greter red color nd color stbility (Renerre, 1990). Animl diets cn influence fresh met color nd color stbility (French et l., 2000; Bublits et l., 2004; Relini, Duckett, Britto, Dll Rizz, & De Mttos, 2004). One exmple is the incorportion of vitmin E into the diets of cttle which retrded lipid nd pigment oxidtion thereby improving color stbility of beef (Fustmn, Cssens, Shefer, Buege, Willims, & Scheller, 1989). The rte of rigor hs n influence on ultimte met ph nd enzyme ctivity (Renerre, 1990). Cuts with lower ph vlues hve reduced enzyme ctivity nd promote utoxidtion of myoglobin (Renerre, 1990). Extrinsic Fctors Temperture Once met products re displyed for customers in retil stores, physicl fctors begin to influence the color of fresh met. Temperture is considered to hve one of the lrgest impcts on met color stbility (McDougll, 1982). Lowering disply tempertures 3 to 5 C will retrd discolortion rte by hlf (McDougll & Tylor, 1975). Wvelength reflectnce rtios of met smples stored t 0 C nd 5 C reveled fster ccumultion of metmyoglobin on the met surfce t 5 C by fctor of four (Hood, 1980). Enzyme respirtory ctivity increses with incresing tempertures leding to incresed OCR nd decresed oxygen pressure (Renerre, 8

24 1990). Keeping disply tempertures low suppresses enzyme ctivity nd llows oxygen to penetrte deeper into the met surfce creting thicker lyer of oxymyoglobin bove the metmyoglobin lyer (Renerre, 1990). Grinding Grinding met will influence the disply color. Met ground twice ws found to destroy the reducing bility of met leding to fster ccumultion of discolortion (Ledwrd et l., 1977). Ground muscle ws found to discolor five times fster thn oxymyoglobin in solution leding to the possibility tht inherent ctlysts re mixed with pigments through grinding (Ledwrd et l., 1977). Govindrjn & Hultin (1977) stted tht grinding compromises the integrity of the cellulr structure nd combines unsturted lipids from the membrne with ctlytic oxidizing regents leding to lipid oxidtion products tht cn oxidize oxymyoglobin. Metmyoglobin formtion is lso found in res of low oxygen pressure cused by grinding met (Kropf, 1980). Bcteril Contmintion Bcteril contmintion of product ffects fresh met color. Short loins inoculted with Pseudomons frgi expressed greter discolortion compred to control smples (Bl, 1977). Aerobic bcteri such s Pseudomons, Achromobcter nd Flvobcterium metbolize oxygen reducing the oxygen pressure t the met surfce resulting in n increse in metmyoglobin content (Renerre, 1990). Beef steks inoculted with erobic bcteri hd oxygen uptkes greter thn 160 µl/30min compred to control steks t pproximtely 20 µl/30min (Robch & Costilow, 1961). Myoglobin denturtion cn occur when proteolytic enzymes from bcteri come into contct with the pigment (Lwrie, 1985). Soniclly treted cell-free Pseduomons genicult popultions were inoculted onto beef steks tht discolored fster thn the controls suggesting tht the bcteri s enzymes cused discolortion (Robch & Costilow, 1961). Lwrie lso suggests discolortion of fresh met cn be relted to pigments produced by microorgnisms. A green discolortion my pper on fresh met from the interction of the hydrogen peroxide by-products from bcteri (Jensen, 1945) nd myoglobin producing Choleglobin (Lwrie, 1985). Nicol, Shw, nd Ledwrd (1970) found n increse in green discolortion with the presence of hydrogen sulfide produced by bcteri on met products with ph vlues 6 or greter. Interventions to control microbiologicl growth through the use of 9

25 products such s potssium sorbte, sodium cette, sodium tripolyphosphte, nd/or tetrsodium pyrophosphte cn prevent metmyoglobin formtion (Renerre, 1990). Chilling Rte The rte t which the temperture of muscle on crcss declines ffects the visul, instrumentl, nd color stbility of met products (Smmel, Hunt, Kropf, Hchmeister, Kstner, & Johnson, 2002). Muscles further from the crcss surfce will decrese in temperture t slower rte nd proceed through glycolysis fster (Smmel et l., 2002). Rpid rtes of glycolysis led to fster ph declines which denture proteins nd open up muscle structure cusing light scttering effects tht re negtive to met color (McDougll, 1982). The color of vcuum pckged beef muscles ws more uniform over 5 d disply t 3 C when excised 1-2 h fter hrvest compred to 48 h (Nichols & Cross, 1980). Smmel et l. (2002) found similr CIE *, oxymyoglobin nd metmyoglobin percentges for hot-boned deep portions nd cold-boned superficil portions of semimembrnosus steks. Visul color scores indicted better color stbility for the superficil nd deep portions of hot-boned nd the superficil portion of coldboned semimembrnosus steks compred to the cold-boned deep portion on d 3. Furthermore, Smmel et l. (2002) found chilling rtes decresed erobic reducing ctivities nd ffected the color stbility of met. Therefore, muscles with more rpid chilling rtes will hve incresed redness, decresed discolortion, nd greter consumer ppel. Oxygen Pressure The mount of oxygen vilble to bind with myoglobin ffects the stte of myoglobin. Oxygen prtil pressures of mmhg provide the optimum level to promote metmyoglobin formtion in muscle foods (George & Strtmn, 1952). Oxygen pressures below 1.4 mmhg promote the deoxygented stte of myoglobin (Mncini & Hunt, 2005). Excluding oxygen entirely from the environment surrounding met products minimizes metmyoglobin formtion (Fustmn & Cssens, 1990). Vcuum pckging met products lmost elimintes oxygen pressure resulting in prevention of utoxidtion (Tylor, 1985). When oxygen is present, the mount of pressure influences the depth of oxygen penetrtion beneth the met s surfce (Mncini & Hunt, 2005). High OCR hve been suggested to prevent the development of oxymyoglobin (Ashmore, Prker, & Doerr, 1972). Oxygen consumption rtes hve been shown to differ between species t 48 h postmortem with lmb hving greter rte thn pork which is 10

26 greter thn beef. With the greter OCR, lmb cn be expected to hve lower color stbility compred to pork nd beef (Atkinson & Follett, 1973). Oxygen consumption rtes were found to differ between muscles (Morley, 1971). Mincing of postrigor muscle does not ffect the oxygen consumption rte (Bendll & Tylor, 1972), but mincing does crete loclized res of low oxygen pressure leding to metmyoglobin formtion (Kropf, 1980). Lipid Oxidtion Lipid nd oxymyoglobin oxidtion re interrelted in fresh met products (Schefer, Liu, Fustmn, & Yin, 1995) nd cn be ctlyzed from by-products of both processes (Liu, Lnri, & Schefer, 1995). Chn nd others (1997) found tht the secondry lipid by-products propionl, decnl, nonnl, hexnl, 2-nonenl nd 2-heptenl ccelerted oxymyoglobin oxidtion compred to control. Holstein gluteus medius ground met metmyoglobin formtion hd correltion coefficient of 0.91 with TBA vlues (Fustmn et l., 1989). Sumn, Fustmn, Stmer, & Liebler (2006) looked t the effect of the ldehyde lipid oxidtion by-product 4- hydroxy-2-nonenl on the oxidtion of oxymyoglobin nd found strong correltion in beef products. Additionlly, lipid peroxidtion promotes metmyoglobin formtion in muscle foods (Knner, 1994). Incresed levels of unsturted ftty cids in liposome nd microsome membrnes hve been found to ccelerte oxidtion of oxymyoglobin (Yin & Fustmn, 1994). Ascorbic cid will ct s n oxygen scvenger s well s n ntioxidnt with nturl nd synthetic ntioxidnts to retrd lipid oxidtion nd prevent metmyoglobin formtion (Renerre, 1990). Reduction in the formtion of thiobrbituric-cid rective substnces (TBARS) nd metmyoglobin ccumultion occurred when higher inherent levels of lipid-soluble α-tocopherol ntioxidnts were present in beef (Yin, Fustmn, Riesen, & Willims, 1993). Met color is complex concept with both extrinsic nd intrinsic fctors intercting nd influencing the outcome of disply color. An understnding of ll the fctors will result in mximizing color life of fresh retil met products. Pckging Pckging is vitl component of met products s it provides protection from physicl, chemicl, nd biologicl hzrds s well s contining the product, communicting to consumers s mrketing tool, nd providing ese of use nd convenience (Ym, Tkhistov, & Miltz, 11

27 2005). A vriety of pckging options exist dding complexity to fresh met color. Color will vry between met products pckged in modified tmosphere (MAP) or plced on try nd overwrpped with plstic wrp. The most common styles of pckging met products for retil disply re wrp on Styrofom try nd MAP (Chrles, Willims, & Rodick, 2006). Polyvinyl Chloride Pckging Polyvinyl chloride pckging with Styrofom try ws the first style of pckging put into prctice when lighted self-service refrigerted met cses were integrted into retil mrkets (McMillin, 2008). The flexible plstic wrp is not only moisture brrier but lso ir-permeble llowing oxygen to contct the met surfce creting the bright red color of oxymyoglobin (Brody, 2002). Consumers seeing met displyed for the first time ssocited the bright red color with freshness nd wholesomeness for prepckged met products (Jenkins & Hrrington, 1991). Although the pckging llows for bloom to occur, the color stbility of fresh met is not n dvntge for this pckging system. Visul nd instrumentl evlutions of discolortion on porcine vertebre reveled disdvntge for pckging (Rines, 2006). Instrumentl */b* (with lower scores indicting greter discolortion) for pckged vertebre were between 0.99 to 1.07 compred to 1.20 to 1.31 for low-oxygen MAP nd 1.02 to 1.24 for high oxygen MAP (Rines, Dikemn, Grobbel, & Yncey, 2006). Moreover, visul color scores of smples were more discolored on d 8 thn high oxygen MAP (Rines et l., 2006). Polyvinyl chloride pckging influences other qulity spects of fresh met. Longissimus dorsi steks stored in pckging hd n incresed ph level, drker color, greter lipid oxidtion nd greter mesophilic popultions compred to vcuum pckged or MAP steks (D Agt, Nuvoloni, Pedonese, Russo, D Ascenzi, & Preziuso, 2010). Therefore, is not conducive to prolonging the color shelf life of fresh met products. Modified Atmosphere Pckging Modified tmosphere pckging involves the removl of ir or substitution of ir with specific tmosphere encompssing the food item within seled vpor-brrier mterils (McMillin, Hung, Ho, & Smith, 1999). Mny benefits exist for MAP rnging from shelf life to met qulity. Due to the economic influencer of centrlly pckged mets nd consumer driven 12

28 need for incresed convenience, cse-redy pckging such s MAP hs penetrted the retil mrket t growing rte (Eilert, 2005). Cse-redy fresh met products incresed 11% in liner footge in the self-service met disply from 2002 to 2004 with 95% of the poultry products displyed in cse-redy formt such s MAP (Eilert, 2005). The increse in MAP pckged products is result of n rry of tmospheres developed for confronting unique phenomen in met products. High oxygen tmospheres re conducive to mintining the bright red bloomed color ssocited with fresh beef (McMillin, 1996). Color pnelists in study indicted more desirble color up to d 4 of disply for beef longissimus lumborum steks pckged in high oxygen tmosphere compred to low-oxygen (Grobbel, Dikemn, Hunt, & Milliken, 2008). However, by d 7 the steks in the low-oxygen tmosphere were more desirble. Ground turkey in MAP contining 8% O 2 with CO 2 nd N 2 comprising the remining mount hd lower * vlue compred to ground turkey pckged in only 20% CO 2 nd 80% N 2 (Sucier, Gendron, & Griépy, 2000). Other gses cn be incorported into pckging to trget specific qulity or shelf life chrcteristics. Atmospheres contining 1% CO compred to high oxygen tmosphere without CO resulted in reduction of psychrotrophic bcteri popultions on beef loin steks nd ground beef (Luño, Beltrán, & Ronclés, 1998). Low oxygen tmospheres offer lterntive benefits, but come with the chllenge of undesirble color. Met products either vcuum pckged or pckged in low oxygen MAP possess reduced oxidtive rncidity leding to more plesurble eting experience for the consumer (Eilert, 2005). With low concentrtions of oxygen, the purple deoxymyoglobin pigment will dominte myoglobin concentrtion; color deemed less desirble thn the bright red oxymyoglobin (McMillin, 2008). Oxygen scvengers, needed to mintin low oxygen tmosphere, incorported into nerobic pckges will led to incresed product cost s well. (McMillin, 2008). Retil Disply Lighting Effect on Met Shelf Life The met industry is wre of the mjor role lighting type nd intensity hs on the ppernce of met in retil disply. Kropf (1980) hs provided n exhustive review of retil disply lighting effects on met color. Energy from lighting ctlyzes the formtion of metmyoglobin in fresh, frozen nd cured mets (Renerre, 1990). Not only does lighting ffect 13

29 fresh met color but lso odor, microbil growth, nd lipid oxidtion (Kropf, 1980; Djenne, Sánchez-Esclnte, Beltrán, & Roncáles,2003; Mrtínez, 2007; & Andersen & Skibsted, 1991). Lighting Effect on Odor Odor of fresh met products ws found to be ffected by light source. Fresh pork susges held in the drk or displyed under fluorescent lighting with UV-filter remined cceptble to pnelists four dys longer thn susges under stndrd fluorescent lighting (Mrtínez, 2007). Beef steks pckged in MAP displyed under low UV or UV-free lighting were reported to hve less perceivble off-odors on d 20 compred to smples under stndrd fluorescent lighting (Djenne et l., 2003). Lighting Effect on Microbil Popultions Mclen, McGregor, Anderson, & Woolsey (2009) hve shown the inctivtion of pthogens using 405 nm wvelength LED light. Suspended cultures were exposed to highintensity LED light for up to 400 min. At 30 min of light exposure, log reductions from 2.6 to 5.0 could be seen for Stphylococcus ureus, Clostridium perfringens nd Escherichi coli. Although this lighting showed n effective method of reducing pthogens, retil disply lighting with wvelength ner the UV spectrum is detrimentl to product color nd the high intensity of the lighting is imprcticl for refrigerted disply. There hs been limited reserch on the effect of trditionl disply lighting on microbil popultions. Stndrd fluorescent lighting incresed psychrotropic erobic popultions on fresh pork susges stored t 2 C tht were pckged in collgen csings plced on polypropylene trys inside pouch mde of polyethylene nd polymide lminte with high oxygen tmosphere. Psychrotropic erobic popultions incresed from the fourth dy of disply to the end of disply under stndrd fluorescent lighting compred to smples displyed in the drk or under UV-filtered lighting (Mrtínez, 2007). Beef steks pckged on polystyrene trys in high oxygen pouch mde of polyethylene nd polymide lminte nd displyed t 1 C under stndrd fluorescent lighting nd UV-free lighting hd similr results, but significnt differences were not observed until d 15 of disply (Djenne et l., 2003). The disply time difference in observing significnt vrition cn be ttributed to lower initil counts s well s ntioxidnt ingredients used with the beef steks. In contrst, fresh prerigor pork susge ptties displyed in 14

30 either drk room or under 2150 lux fluorescent lighting showed no differences in totl erobic plte counts (Seyfert, Hunt, Grobbel, Ryn, Johnson & Monderen, 2006). Lighting Effect on Lipid Oxidtion Photooxidtion of lipids s result of disply lighting occurs in met products. Fresh pork susges held in the drk or displyed under fluorescent lighting with UV-filter recorded lower TBARS vlues (Mrtínez et l., 2007). Smples with TBARS vlues bove 1.5 hd detectble odor ccording to pnelists; correltion between pnel odor scores nd TBARS vlues existed t 0.93 (Mrtínez et l., 2007). Therefore, TBARS vlues cn be used to determine detectble levels of lipid oxidtion by consumers for fresh pork susge. A study with frozen pork ptties by Anderson & Skibsted (1991) hs linked UV light to inducing photooxidtion of lipids which is in greement with results from studies by Mrtínez et l. (2007) with fresh pork susge nd Djenne et l. in 2003 involving beef longissimus dorsi steks. Lighting Effect on Color Disply cse lighting hs considerble influence on met color stbility. The met industry is wre of the mjor role lighting type nd intensity hs on the ppernce nd shelf life of met on disply. Correlted color temperture (CCT), color rendering index (CRI) nd the color spectrum of light source ffect ppernce (Konic Minolt, 2007) nd color stbility of fresh met products. CCT is mesured in kelvin nd reltes directly to the color of the rdint energy reflected from the object (Konic Minolt, 2007). Drker objects, such s red mets, will record lower CCT vlues compred to lighter colors while light pigmented mets will hve higher CCT vlues. Lighting sources with CCT s closest to the color of the object under disply will hve the most desired ppernce to observers. The AMSA Guidelines for Met Color Evlution recommend Illuminnt A with CCT of 2856 K (Konic Minolt, 2007) s the light source for instrumentl color mesurement of smples becuse it correltes best with visul color scores nd hs stronger emphsis on the red portion of the color spectrum. Color rendering index is mesurement on scle from 1 to 100, with 100 being the most desirble, describing the bility of light source to portry colors of n object ginst perfect light reference (DOE, 2011). When lighting sources hve low CRI vlues, undesired effects in ppernce occur such s pinkish ft or yellowish bone (Kropf, 1980). Color is prt of the electromgnetic 15

31 spectrum spnning from 380 to 780 nm (Konic Minolt, 2007) with violet hving the shortest wvelength nd red possessing the lrgest wvelengths. Therefore, light source with n emission spectrum mostly in the red section between 630 nm nd 700 nm is desirble for fresh red mets (Kropf, 1980). Reserch hs shown significnt differences in color shelf life for met products displyed under different lighting sources. As discussed under extrinsic fctors, elevted tempertures promote discolortion of met. Any lighting type with incresed operting temperture is detrimentl to fresh met color (Hood, 1980). Disply lighting photochemicl effects impct color s well (Renerre, 1990). Ultrviolet light penetrtes into met nd dentures the globin in myoglobin cusing discolortion (Lwrie, 1985). Visul evlution of pork susges displyed under fluorescent lighting with UV-filter plte of polycrbonte indicted n end to color shelf life t d 12 versus products displyed under trditionl fluorescent lighting or low-uv with color life ending on d 8 (Mrtínez, 2007). Instrumentl * vlues supported the extended color life with smples displyed in the drk nd under UV-filter being greter thn smples displyed under stndrd or low-uv lighting for the first 8 dys of disply (Mrtínez, 2007). Studies from Djenne, Sánchez-Esclnte, Beltrán, & Roncáles (2001) nd Bertelsen nd Boegh-Soernesen (1986) resulted in similr conclusions ttributing UV light to severely discoloring fresh met. New technologies in lighting offer lterntive pthwys for confronting not only met color, but lso other costly inputs for met retil disply. Light Emitting Diode (LED) lighting offers numerous dvntges for disply due to being more energy efficient nd generting less het. LED Lighting LED technology begn in the 1950 s with commercil production strting in the lte 60 s (DOE, 2009). Currently, less thn n estimted 1% of the refrigerted disply cses hve LED lighting technology instlled (DOE, 2008). According to LED Mgzine (2011), 1,463 compnies round the world distribute LED lighting. Phosphor converted LEDs hve higher efficcies compred to incndescent nd compct fluorescent light bulbs leding to significnt energy svings (Arik, 2009). One study conducted in Eugene, Oregon Albertsons retil grocery store compred the energy svings of LED lighting versus FLS lighting in freezer cses. Four 5- door upright freezer cses nd two 3-door freezer cses were retrofitted with LED lighting while the sme set up on the opposite side of the isle contined fluorescent lighting. The freezer cses 16

32 with LED lighting pulled 1.6 fewer mps reducing wttge 192 wtts per 5-door cse leding to 61% energy svings per yer (PNNL, 2009). However, the instlled LED lighting hd 36% reduced illuminnce compred to the fluorescent lighting becuse the fluorescent lighting ws bove typicl industry recommendtions. A portion of the energy svings cn be ttributed to the lower illuminnce (PNNL, 2009). The United Sttes Deprtment of Energy (DOE) relizes the potentil cost nd energy svings LED lighting holds due solely to the efficiency. Gols hve been set for the fiscl yer 2015 to produce LED lighting systems costing less thn $2/klm with CRI greter thn 80, correlted CCT less thn 5000 K, nd 126 lm/w luminire tht emits pproximtely 1000 lumens (DOE, 2009). Currently, wrm white LED systems with CCT less thn 3300 K possess lm/w while compct fluorescent lighting possesses lm/w. Although both technologies possess similr efficcies, FLS technology is in its mture stges while LED systems hold the potentil to improve two-fold on energy efficiency (DOE, 2009). In ddition, LED lighting provides longer operting life, lower mintennce nd life cycle costs, miniml light loss, directionl illumintion, djustble color, nd uniform illumintion (DOE, 2008). LED lighting will mke strong ppernce in retil disply met cses with potentil cost nd energy svings nd lower het genertion. Energy svings up to 2.1 TWh of electricity is possible if the entire refrigerted mrket switched to LED lighting (DOE, 2008). As LED lighting provides lower energy costs, longer operting life, nd lower operting tempertures, reserch is needed to evlute how LED lighting ffects the color stbility nd shelf life of fresh met. Reltionship Between Visul nd Instrumentl Color Visul Color Evlution According to the Americn Met Science Assocition (1991), visul color pnels re closely relted to consumer perceptions of met products. There re two types of visul color pnels, preference nd descriptive. Preference evlutions use untrined pnelists to estimte consumer preferences while descriptive evlutions use trined color pnelists to detect differences between tretments. Vribility in results cn come from the repetbility of humn judgement, lighting, visul deficiencies of the eye nd ppernce fctors other thn color. To minimize vribility, pictoril color stndrds nd pproprite scles must be customized to ech 17

33 color pnel. Preliminry studies result in scles tht will encompss the spectrum of smple colors most likely to pper throughout the study. Mny descriptive scles re used in visully evluting met color. Worst point color scles sk pnelists to score the most discolored 2 cm re of product wheres overll color scles verge the discolortion cross the entire surfce of product. Percent discolortion nd consumer preference scles re used to determine time periods for retil discounting or discrding products long with estimting consumer preferences. Instrumentl Color Anlysis The Met Color Mesurement Guidelines from the Americn Met Science Assocition (1991) report tht instrumentl color mesurements re used to provide objective results to support visul observtions, provide bsis for product cceptnce or rejection, document color deteriortion over time nd estimte the proportion of myoglobin sttes. Instrumentl dt must be used to represent reltive color differences s opposed to bsolute descriptions of color. Product color cn be instrumentlly mesured either through pigment extrction or reflectnce. The reflectnce color mesurement method is more rpid pproch tht cn be used repetedly on the sme smples. For met smples, illuminnt A should be the light source used s it plces more emphsis on the red portion of the color spectrum nd correltes with visul scores better. Reflectnce dt cn be reported s CIE Lb-vlues lso known s L* (light), *(red) nd b*(yellow). Hue ngle (tn -1 b*/*), /b (*/b*) nd sturtion index ((* 2 + b* 2 ) (1/2) ) re clcultions of instrumentl dt used to monitor discolortion. Lower vlues of /b nd sturtion nd higher vlues of hue ngle re indictors of discolortion (AMSA, 1991). Reltionship of Visul nd Instrumentl Color Describing nd evluting color for humns is subjective prctice. Consumers psychologiclly perceive color by mixture of stimuli from three primry colors which cn be mesured in physicl quntities (McDougll, 1982). One study sked pnelists to ctegorize beef longissimus dorsi steks into one of 10 reference stndrds using visul color nd compred those results with instrumentl color mesurements ctegorizing the steks. Using L**b*C*nd H*, instrumentl mesurements plced the steks in the sme ctegory s visul observtions 83.3% of the time (Goñi, Indurin, Hernndez, & Berin, 2007). Jeremih et l. (1972) found 18

34 visul color to correlte with instrumentl vlue nd chrom 81% nd 73% of the time, respectively. Pork longissimus lumborum visul color ws reported to hve 92% nd 90% correltion with illuminnt A-Hunter L* nd hue ngle vlues, respectively (Brewer, Zhu, Bidner, Meisinger, & McKeith, 2000). 19

35 CHAPTER 3 - Shelf Life of Five Met Products Displyed Under Light Emitting Diode or Fluorescent Lighting Abstrct Light Emitting Diode (LED) lighting used in retil disply cses offers economicl svings in energy use nd genertes less het compred with fluorescent (FLS) lighting. This study compred the effects of LED nd FLS lighting on visul nd instrumentl met color nd shelf-life properties of five met products displyed in two Hussmnn retil disply cses set up with the sme opertionl nd temperture profiles so tht lighting ws the single vrible. For ech tretment, 24 enhnced pork loin chops, 36 beef longissimus dorsi steks, 24 ground beef, 24 ground turkey, nd 36 beef semimembrnosus steks were used. Pork loin chops nd beef longissimus dorsi steks were received in mother bgs contining 0.4% CO 35% CO % N 2. Beef semimembrnosus steks were cut fresh from subprimls prior to disply. Ground turkey ws displyed in high-oxygen (75% O 2 nd 19% CO 2 ) modified tmosphere pckging (MAP) while the remining products were displyed on fom trys with moisture bsorbent pds nd overwrpped with polyvinyl chloride film. Visul color, instrumentl color, internl product tempertures, cse tempertures nd thiobrbituric cid rective substnces (TBARS) vlues nd except for beef semimembrnosus steks, erobic plte counts (APC) nd Enterobctericee counts (EB) were mesured. As expected, visul color scores of the five met products indicted color deteriortion incresed s disply time incresed. Beef longissimus dorsi steks, ground beef, nd the superficil portion of beef semimembrnosus steks hd less (P<0.05) visul discolortion under LED lighting thn FLS. For instrumentl color, pork loin chops under LED lighting hd higher (P<0.05) L* vlues. The superficil nd deep portions of beef semimembrnosus steks were slightly (P<0.05) more intense red under LED lighting. For ll other products, no differences (P>0.05) were found for * vlues or sturtion indices. There ws no lighting type min effect (P>0.05) on APC or EB popultions. Pork loin chops nd ground turkey hd lighting type by dy interction for APC nd EB popultions, respectively. At the end of disply, chops under LED lighting hd lower APC popultions thn FLS. Ground turkey under FLS lighting 20

36 fluctuted throughout disply with higher EB popultions t the end compred to smples under LED lighting remining constnt throughout the study. As expected, APC popultions incresed s disply time incresed for pork loin chops, ground beef, nd ground turkey. APC popultions for beef longissimus dorsi steks did not chnge (P>0.05) during disply, however disply life ws limited due to initil cse-redy ge. EB popultions incresed (P<0.05) for pork loin chops, ground beef nd ground turkey s disply time incresed. The internl temperture of ll products, except beef longissimus dorsi steks, ws lower (P<0.05) in the LED cse. FLS cse tempertures were higher (P<0.05) by 0.56 to 1.11 C over the durtion of the study compred to the LED cse. Pork loin chops, ground turkey, nd beef semimembrnosus steks hd higher (P<0.05) TBARS vlues by 0.06 to 0.24 mg mlonldehyde/kg under LED lighting, but lighting type did not ffect (P>0.05) TBARS of beef longissimus dorsi steks or ground beef. LED lighting results in lower disply cse tempertures, lower internl product tempertures, nd extended color life; however, lipid oxidtion ws incresed in some cuts under LED lighting. Introduction Retil customers do not hve methods to estimte tenderness, juiciness or flvor when evluting met cuts for purchse. Insted, color is one of the mjor criteri in selecting met items (Kropf, 1993). During refrigerted disply, fresh met color chnges nd customers discriminte ginst discolored mets. Met items with discolortion must be discounted or discrded leding to revenue losses up to $1 billion for the met industry (Smith, Belk, Sofos, Ttum, & Willims, 2000). Myoglobin is the primry pigment responsible for met color. Pigment concentrtion nd the physicl prmeters of met, including light scttering nd bsorbing properties, ffect met color (Kropf, 1993). Myoglobin protein exists s deoxymyoglobin, oxymyoglobin, or metmyoglobin depending upon the stte of the iron molecule s well s the occuption of the sixth lignd (Fustmn & Cssens, 1990). Met color is the result of the interction of mny fctors (Kropf, 1993). These fctors include interction of metmyoglobin reducing ctivity, disply tempertures, oxygen pressure nd consumption rte, bcteril contmintion, lipid oxidtion, niml diet, niml genetics, nd niml breed (Ledwrd, Smith, Clrke, & Nicholson, 1977; McDougll & Tylor 1975; George & Strtmn, 1952; Bl, Mrshll, Stringer, & Numnn 1977; Chn, Fustmn, & Decker, 21

37 1997; French, Stnton, Rwless, O Riordn, Monhn, Cffery, & Moloney 2000; Brewer, Jensen, Sosnicki, Fields, Wilson, & McKeith, 2002; Brewer, Sosnicki, Fields, Hnkes, Ryn, Zhu, & McKeith, 2004). These vribles must be well understood in order to contend with the complexity of met color. The met industry is wre of the mjor role lighting type nd intensity hs on the ppernce of met in retil disply. Lighting technology hs developed to extend fresh met color. Newer technologies in lighting offer the bility to enhnce met color plus reduce other costly inputs for met retil disply. Light emitting diode (LED) lighting offers dvntges for disply by being more energy efficient nd hving reduced het genertion throughout disply. Currently, less thn n estimted 1% of the refrigerted disply cses hve LED lighting technology instlled (DOE, 2008). Phosphor converted LEDs hve higher efficcies compred to incndescent nd compct fluorescent light bulbs leding to significnt energy svings (Arik, 2009). The Deprtment of Energy (DOE) relizes the potentil cost nd energy svings LED lighting holds due solely to efficiency. Gols hve been set by the United Sttes government for the fiscl yer 2015 to produce LED lighting systems costing less thn $2/klm with colorrendering index (CRI) greter thn 80, correlted color temperture (CCT) less thn 5000 K, nd 126 lm/w luminire tht emits pproximtely 1000 lumens (DOE, 2009). Furthermore, LED lighting provides longer operting life, lower mintennce nd life cycle costs, miniml light loss, directionl illumintion, djustble color, nd uniform illumintion (DOE, 2008). Energy svings up to 2.1 TWh of electricity is possible if the entire refrigerted mrket converted to LED lighting (DOE, 2008). As LED lighting provides potentil for lower energy costs, longer operting life, nd lower operting tempertures, reserch is needed to evlute how LED lighting ffects the color stbility nd shelf life of fresh met. The objective of this study ws to determine the effects of LED nd FLS lighting on visul nd instrumentl met color nd shelf-life properties of five fresh met products displyed in two retil disply cses running t similr temperture profiles. Mterils nd Methods 22

38 Retil Disply Cses Two Hussmnn Ingersoll 8 foot M5X (Bridgeton, MO) met retil disply cses were instlled in the Knss Stte University (KSU) Met Color Lb. One cse ws equipped with FLS lights, the other with LED lights. The cses were instlled end-to-end with condenser units equipped with n on/off cycle counter nd n hour meter in n djcent room. Defrost cycles occurred simultneously every six h. To minimize end-temperture fluctutions nd to simulte end-to-end cse plcement, 1.03 x 1.74 x.05 m piece of Owens Corning Formultor 150 insultion (Toledo, OH) ws ttched to the outside end of ech cse. Cse tempertures were djusted to operte s close s possible with cse lighting off nd similr condenser cycling. Tempertures were confirmed with 30 RD-Temp-XT Temperture Loggers (Omeg Engineering, Stmford, CT) to be similr during 2-3 d of drk opertion before d 0 of the study. Ech disply cse hd four djustble shelves consisting of two sections nd the fixed bottom shelf. The top shelf width ws cm, shelf 2 ws cm, shelves 3 nd 4 were cm, nd the bottom shelf ws cm wide. Shelves were rrnged identiclly in both cses nd were similr in verticl spcing to cses in Mnhttn, KS supermrkets. As product ws removed from cse for nlyses, 454 g plstic wter bg ws positioned in the vcnt loction to simulte full disply cse. The verge room temperture ws 18.3 C. Disply Lighting The met products in both cses were illuminted 24 h/d. In the LED cse, cnopy lighting fixture (Hussmnn EcoShine Model Nos nd , Bridgeton, MO) positioned bove the top shelf hd CCT of 2867 K nd CRI of 93. The bottom four shelves were illuminted with LED light brs (Hussmnn EcoShine Model No , Bridgeton, MO) hving CCT of 3007 K nd CRI of Lighting intensity in the LED cse verged 1627 lm. The FLS lighting (Sylvni Octron, F032/835/ECO, Dnvers, MA) hd CCT of 3500 K, CRI of 82 nd lighting intensity verging 1712 lm. Cse Tempertures Cse tempertures were monitored throughout the study using I-button Thermochrons (DS1921 G Mxim Direct, Sunnyvle, CA). Six I-buttons were locted on ech shelf with two 23

39 ech on the fr left, fr right, nd center positions of ech shelf for totl of 30 temperture dt loggers per cse (Fig. 3-1). Tempertures were recorded every ten min throughout the study. Fig I-button temperture logger loctions in fluorescent (FLS) nd light emitting diode (LED) disply cses. Chrt 1- I-button temperture logger loctions. Shelf 1, Top FLS nd LED Cses , Bottom Rw Mterils nd Pckging for Disply Five types of fresh met products were obtined from commercil supplier (Crgill Met Solutions, Wichit, KS) nd stored in 4.4 C cooler for up to 2 d before reprocessing nd/or repckging for disply. Pork loin chops: Pork loin chops (1.91 cm thick, 6 d postmortem) enhnced t 12% with pork stock, lctte, phosphte, slt, nd nturl ingredients were received in pckges of four chops enclosed in mother bg which hd been flushed with 0.4% CO 35% CO % N 2. Chops were rndomly selected from the mother bg nd individully pckged on x x 1.27 cm 1S fom trys (Dyne--pk Inc., Lvl, QC, Cnd) with Dry-Loc (c-50, Cryovc, Duncn, SC) moisture bsorbent pds nd overwrpped with polyvinyl chloride () film (23,250 cc/m 2 C nd 0% RH, Borden Pckging nd Industril Products, North Andover, MA). 24

40 Beef longissimus dorsi steks: United Sttes Deprtment of Agriculture (USDA) select/low choice beef longissimus dorsi steks enhnced t 8% pump with beef stock, lctte, phosphte, slt nd nturl flvorings were received s individully pckged steks (1.27 cm thick, 9 d cse-redy dte) on fom trys with overwrp in mother bg which hd been flushed with 0.4% CO 35% CO % N 2. Steks were removed from the no-oxygen mother bg, nd individully re-pckged on x x 1.43 cm 17S fom trys contining moisture bsorbent pd nd overwrpped with. Ground beef: Corse ground beef (85% len nd 15% ft) ws received in 4.54 kg chubs. On d 0, corse ground beef ws re-ground t the KSU Met Lb through 0.32cm plte, nd then 454 g ground beef ws plced on moisture bsorbent pd on x x 1.59 cm fom trys nd overwrpped with. Ground turkey: Ground turkey contining rosemry ws cse-redy, in 454 g/modified tmosphere pckge (MAP) contining 70% O 2 20% CO 2 10% N 2. Beef semimembrnosus steks: One dy prior to disply, vcuum pckged USDA select/low choice beef semimembrnosus subprimls were trimmed of externl ft nd the dductor muscle t KSU, re-vcuum pckged, nd then stored in 4.4 C cooler. On d 0, steks were mnully cut 2.54 cm thick nd plced on moisture bsorbent pd on x x 1.27 cm fom trys nd overwrpped with. Within ech product type, products were rndomly selected for repliction nd disply loction on specific shelf. The top shelf of ech cse held four replictions of six enhnced pork loin chops, the second shelf held six replictions of six beef longissimus dorsi steks, the third shelf held four replictions of six ground beef, the fourth shelf held four replictions of six ground turkey, nd the bottom shelf held six replictions of six beef semimembrnosus steks. In totl, 48 enhnced pork loin chop pckges, 72 beef longissimus dorsi stek pckges, 48 ground beef pckges, 48 ground turkey pckges, nd 72 beef semimembrnosus stek pckges were evluted for initil ph, visul nd instrumentl color, internl temperture, subjective odor, thiobrbituric cid rective substnces (TBARS), nd except for beef semimembrnosus steks, microbil popultions during disply. Pckged products were put into disply immeditely fter finl pckging (d 0) nd displyed until the end of visul color life s determined by n verge visul color pnel score of 4. 25

41 Initil ph The met ph of ll rw mterils ws mesured on 4 to 8 rndomly selected smples from ech repliction on d 0 by inserting ph probe (Hnn Instruments; H199163; Woonsocket, RI) ttched to n Accumet Bsic ph Meter (Fisher Scientific, Pittsburgh, PA) into the smples t three loctions. Visul Color All visul pnelists hd pssed the Frnsworth-Munsell 100-Hue Test for color blindness nd bility to detect differences in hue nd were oriented with ctul product, pictoril references, nd the scoring bllot before the study strted. A minimum of 8 trined color pnelists evluted met color dily to the nerest 0.5 increment using 8-point scles unique to ech product. Pork loin chop nd ground turkey visul color scle: 1= very bright reddish pink, 2= bright reddish pink, 3= dull reddish pink, 4= slightly gryish pink, 5= gryish pink, 6= slightly tnnish gry, 7= modertely tnnish gry, 8= tn to brown. Beef longissimus dorsi nd superficil portion of semimembrnosus steks, nd ground beef color scle: 1= very bright red, 2= bright red, 3= dull red, 4= slightly drk red, 5= modertely drk red, 6= drk red to tnnish red, 7= drk reddish tn, 8= tn to brown. Beef semimembrnosus deep portion stek visul color scle: 1= very bright pinkish red, 2= bright pinkish red, 3= dull pinkish red, 4= slightly drk pinkish red, 5= modertely drk pinkish red, 6= drk pinkish red to tnnish pink, 7= drk pinkish tn, 8= tn to brown. An verge visul pnel score of 2.5 nd 4 represented the middle nd end (estimted s the point of objectionble color in retil displys) of product color shelf life, respectively. The color of pork loin chops, beef longissimus dorsi steks, ground turkey, nd beef semimembrnosus steks were evluted by pnelists once per dy t stndrdized time. The superficil nd deep portions of semimembrnosus steks were evluted seprtely for color. Ground beef ws visully scored every 12 h through d 2 of disply, nd then every 24 h for the remining disply time. Instrumentl Color Two pckges from ech replicte were nlyzed for CIE L*, *, nd b* for Illuminnt A, n perture of 31.8 mm nd the 10 Observer using HunterLb MiniScn EZ (Model 4500; Reston, VA). Three mesurements were tken on ech pckge through the overwrp film 26

42 for ll products except ground turkey. Color of ground turkey ws determined by removing the MAP film nd directly pressing the perture covered with cler plstic wrp onto the met surfce. Hue ngle, sturtion index nd /b rtios were determined. Mesurements were tken once dily t stndrdized time except for ground beef which ws mesured every 12 h for the first 2 dys, nd ground turkey which ws mesured on d 0, 1, 2, 3, nd 7. Product Internl Temperture Internl product temperture ws mesured dily t the geometric center of one smple per replicte using thermocouple (Omegette HH300 Series Thermometer, Stmford, CT) except for ground turkey which ws mesured on d 0, 1, 2, 3, nd 7. Gs Concentrtion The gs concentrtion in ll of the originl mother bgs for pork loin chops nd beef longissimus dorsi steks were nlyzed using gs nlyzer (Bridge Hi/Lo-Ox Tri Gs MAP CO/CO2/O2 Anlyzer, Model ; Almed, CA). Using the sme gs nlyzer, the tmosphere of one pckge per replicte of ground turkey ws mesured on d 0, 1, 2, 3, nd 7 of disply. Odor Odor ws scored immeditely fter opening pckge on d 0 nd t the end of disply. Three trined odor pnelists subjectively evluted off-odors using five-point scle: 1 = no offodor, 2 = slight, 3 = smll, 4 = moderte nd 5 = extreme off-odor. TBARS Product oxidtion ws nlyzed using the TBARS procedures of Witte et l. (1970). On d 0 nd the end of disply, smple from the upper 0.64 cm of the displyed surfce ws removed with knife nd stored in bg (Whirl-Pk, Nsco, Modest, CA) t -80 C until nlyzed within 30 dys. Microbiology For ech replicte, two pckges of ech product under FLS nd LED lighting except beef semimembrnosus steks were evluted for microbil popultions t the beginning, middle, 27

43 nd end of color shelf life. Initil microbil testing ws performed on d 0 for ll products. The middle smpling dy ws determined by n verge visul color pnel score of 2.5 nd the end with n verge color score of 4. As result, ech product hd unique middle nd end microbil smpling dy. Aerobic Plte Count (APC) nd Enterobctericee (EB) popultions were determined using Petrifilm (3M Microbiology Products; St. Pul, MN). Enhnced pork loin chops were septiclly cored using 2.54 cm dimeter corer to obtin 25 g smple tht ws stomched (Stomcher 400 Lb Blender, Sewrd Medicl, London, UK) with 225 ml sterile 0.1% peptone diluent (Difco, BD) for 1 min in filter bg (FILTRA-BAG, no , Fisher Scientific, Pittsburg, PA). Ech smple ws seril diluted in 0.1% peptone wter nd dilutions were plted in duplicte. For beef longissimus dorsi steks, 50 cm 2 re of smple ws swbbed (BctciSwb II, Remel, Lenex, KS), plced into 9 ml 0.1% peptone diluent, nd seril diluted before plting in duplicte. For ground beef nd ground turkey, 25 g smples collected from the 0.64 cm outer illuminted surfce were stomched for 1 min in 225 ml of 0.1% peptone diluent in filter bgs, serilly diluted with 0.1% peptone, nd then plted in duplicte. Pltes for APC nd EB popultions were incubted t 32 C for 48 h nd 24 h, respectively, prior to enumertion. Sttisticl Anlysis This ws completely rndomized design with sub-smpling. Repliction ws used s covrite. Dt were nlyzed using the PROC Mixed procedure in SAS 9.2. The Kenwrd- Roger (KR) djustment ws used for degrees of freedom. Effects tested in the model included repliction, lighting type (LED vs. FLS), dy of disply, nd the lighting type by dy of disply interction. The lest significnt difference procedure ws used to seprte mens (P < 0.05). Results nd Discussion Min effects nd interctions between lighting type nd dy of disply re summrized in Tbles 1 to 3. 28

44 Tble 1. Probbility vlues for lighting type, dy of disply, nd lighting type by dy of disply interctions for visul nd L*, * nd b* instrumentl color. Sttisticl Anlysis Visul Color Pork Chop Beef longissimus Ground dorsi stek Beef Ground Turkey Beef Superficil Portion semimembrnosus Stek Beef Deep Portion semimembrnosus Stek Lighting Type Dy of Disply < < < < < < Lighting Type by Dy of Disply Instrumentl Color L* Lighting Type < Dy of Disply < < Lighting Type by Dy of Disply * Lighting Type Dy of Disply < < < < Lighting Type by Dy of Disply b* Lighting Type Dy of Disply < < < < Lighting Type by < Dy of Disply 29

45 Tble 2. Probbility vlues for lighting type, dy of disply, nd lighting type by dy of disply interctions for sturtion index, /b rtio nd hue ngle. Sttisticl Anlysis Instrumentl Color Sturtion Index Pork Chop Beef longissimus Ground dorsi stek Beef Ground Turkey Beef Superficil Portion semimembrnosus Stek Beef Deep Portion semimembrnosus Stek Lighting Type Dy of Disply < < < < Lighting Type by Dy of Disply /b Rtio Lighting Type Dy of Disply < < < < Lighting Type by Dy of Disply Hue Angle Lighting Type Dy of Disply < < < < Lighting Type by Dy of Disply

46 Tble 3. Probbility vlues for lighting type, dy of disply, nd lighting type by dy of disply interctions for thiobrbituric cid rective substnces (TBARS), erobic plte counts nd Enterobctericee counts. Sttisticl Anlysis TBARS Pork Chop Beef longissimus Ground dorsi Stek Beef Ground Turkey Beef semimembrnosus Stek Lighting Type Dy of Disply < < < < < Lighting Type by Dy of Disply Aerobic Plte Count Lighting Type Dy of Disply < < Lighting Type by Dy of Disply Enterobctericee Count Lighting Type Dy of Disply Lighting Type by Dy of Disply Initil Conditions Men initil ph of the five products re shown in Tble 4. The ph of beef longissimus dorsi nd semimembrnosus steks were similr (P>0.05). The ph of the ground turkey my be higher due to dded rosemry ingredients. The mother bg gs concentrtion for pork loin chop nd beef longissimus dorsi steks re shown in Tble 4. The MAP tmospheres of ground turkey during storge is shown in Tble 5. These gs mixtures re typicl of high-oxygen supplier specifictions trgeting shelf life of 6-10 d (McMillin, 2008). 31

47 Tble 4. Lest squres mens (Lsmens) for ph of five met products nd gs compositions of products received in mother bgs. Beef longissimus dorsi Steks Beef semimembrnosus Steks Pork Loin Ground Ground Trit Chops Beef Turkey ph 5.78 c 5.62 d 5.92 b d Gs (%) CO CO O d Lsmens within row hving different superscript letter differ (P<0.05). CO= Crbon monoxide, CO 2 = Crbon dioxide, O 2 = Oxygen. Tble 5. Gs composition of pre-pckged modified tmosphere ground turkey during refrigerted disply under fluorescent (FLS) or light emitting diode (LED) lighting. Dy of CO % CO 2 % O 2 % Disply FLS LED FLS LED FLS LED Cse Tempertures nd Cycling Throughout disply, the pooled LED men cse temperture ws 0.84 C which ws lower (P<0.05) thn the FLS cse with pooled men cse temperture of 1.53 C (Fig. 3-2). Tempertures t the front of the shelves t the left, center, nd right cse sections were more thn 1 C higher (P<0.05) compred to the bck of the shelves (Fig. 3-3). Due to smll gp between shelf sections in ech row llowing cool ir to flow freely in the center of the cse, tempertures t the row centers tended to be C lower thn the sides. No differences (P>0.05) were observed for men tempertures between ny of the five shelves. Averge mbient temperture of the room housing the cses ws 18.3 C. The cycles, run hours nd verge cse condenser cycle per hour during disply for LED nd FLS cses re shown in Tble 6. 32

48 Temperture C A ntionl retil survey s cited by Mncini nd others (2002) reported verge disply cse tempertures of 4.4 C for retil met disply. Tempertures used in this study were colder thn tht cited by Mncini nd others (2002). Disply cses equipped with LED lighting recorded fewer condenser cycles/h nd mintined 0.69 C lower cse tempertures thn cses with FLS lighting. Although numerous fctors ffect cse opertion efficiency, lower temperture vlues indicte shelf life dvntges for products held under LED lighting. The cse with LED lighting hd n operting efficiency dvntge while mintining lower cse tempertures compred to the cse with FLS lighting. This grees with 2008 report from the DOE reporting greter compressor energy use due to dditionl het generted from FLS disply lighting. Not only does n LED cse operte with greter efficiency in energy use, but lso sustins lower tempertures thn FLS lighted cse (DOE, 2008). Fig Lest squres mens (Lsmens) for cse temperture pooled from 30 loctions in refrigerted disply cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting FLS b LED Cse b Lsmens with different superscript letters differ (P<0.05). Stndrd error =

49 Temperture C Fig Lest squres mens (Lsmens) for cse temperture 1 t six shelf loctions in refrigerted disply cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b b b -0.5 FL FC FR BL BC BL Loction b Lsmens with different superscript letters differ (P<0.05). Stndrd error = Loctions re: FL= front of shelves on left side of cse, FC= front of shelves in center of cse, FR= front of shelves on right side of cse, BL= bck of shelves on left side of cse, BC= bck of shelves in center of cse, BR= bck of shelves on right side of cse. Tble 6. Disply cse condenser cycling nd run time during disply using fluorescent (FLS) or light emitting diode (LED) lighting. Cse Cycles Run Hours Cycles/h FLS LED Visul Color Evlution Of ll five met products on disply, beef longissimus dorsi steks, ground beef nd the superficil portion of beef semimembrnosus steks hd better (P<0.05) color stbility under LED lighting bsed on evlutions by trined color pnelists (Fig. 3-4), resulting in n extended color shelf life nd economic benefits for retilers. The color shelf life of pork loin chops nd ground turkey, both light pigmented products, ws driven by dy of disply nd not lighting type. No interctions (P>0.05) between lighting type nd dy of disply for visul color existed for ny of the five met products. As expected, visul discolortion incresed for ll products s disply time incresed (Figs. 3-5 to 3-10). End product color shelf life for pork loin chops, beef 34

50 Color Score longissimus dorsi steks, ground beef, ground turkey nd beef semimembrnosus steks, s determined by the pnelists scores were 8, 2, 4, 7, nd 4 d respectively. Visul color evlution for beef longissimus dorsi nd the superficil portion of beef semimembrnosus steks under LED lighting showed n extended color life by 0.5 to 1 dy compred to FLS lighting; however, there ws no significnt interction for lighting type by dy of disply. Semimembrnosus steks typiclly hve two-toned ppernce with the deep portion of the muscle being pler nd more susceptible to discolortion compred to the superficil portion which holds color longer (Smmel et l., 2002; Lee, Yncey, Apple, Swyer & Bublits, 2006). Thus, the inner portion often determines cceptble color life for this muscle. Visul color results shown in Fig. 3-4 demonstrte tht the superficil portion of beef semimembrnosus steks should be displyed under LED lighting for extended shelf life. Fig Lest squres mens (Lsmens) for visul color of five products 1 displyed in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Top Shelf Pork Loin Chop b Shelf 2 Beef Longissimus Dorsi Steks b Shelf 3 Ground Beef Product Shelf 4 Ground Turkey FLS b Bottom Shelf Beef Semimembrnosus Superficil LED Bottom Shelf Beef Semimembrnosus Deep b Lsmens within ech product hving different superscript letter differ (P<0.05). 1 Visul color score: Pork loin chop nd ground turkey 1=very bright reddish pink, 4=slightly gryish pink, 8=tn to brown; beef longissimus dorsi stek, ground beef, beef semimembrnosus superficil 1=very bright red, 4=slightly drk red, 8=tn to brown; beef semimembrnosus deep 1=very bright pinkish red, 4=slightly drk pinkish red, 8=tn to brown. 2 Stndrd error: Pork loin chop=0.03, beef longissimus dorsi stek=0.16, ground beef=0.10, ground turkey=0.05, beef semimembrnosus superficil=0.08, beef semimembrnosus deep=

51 Color Score Color Score Fig Lest squres mens (Lsmens) for visul color 1 of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting f f e d c c c b Dy of Disply b Lsmens with different superscript letters differ (P<0.05). Stndrd error = Color scle rnged from 1 to 8 with 1= very bright reddish pink, 4= slightly gryish pink, nd 8= tn to brown. Fig. 3-6 Lest squres mens (Lsmens) for visul color 1 of beef longissimus dorsi steks over 2 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b c Dy of Disply b Lsmens with different superscript letters differ (P<0.05). Stndrd error = Color scle rnged from 1 to 8 with 1=very bright red, 4= slightly drk red, nd 8= tn to brown. 36

52 Color Score Color Score Fig Lest squres mens (Lsmens) for visul color 1 of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b c e de d 0 morning 0 evening 1 morning 2 morning 3 morning 4 morning Dy of Disply b Lsmens with different superscript letters differ (P<0.05). Stndrd error = Color scle rnged from 1 to 8 with 1= very bright red, 4= slightly drk red, nd 8= tn to brown. Fig Lest squres mens (Lsmens) for visul color 1 of ground turkey over 7 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting e d c c b f g Dy of Disply b Lsmens with different superscript letters differ (P<0.05). Stndrd error = Color scle rnged from 1 to 8 with 1= very bright reddish pink, 4= slightly gryish pink, nd 8= tn to brown. 37

53 Color Score Color Score Fig Lest squres mens (Lsmens) for visul color 1 of beef semimembrnosus deep portion steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b c d e Dy of Disply b Lsmens with different superscript letters differ (P<0.05). Stndrd error = Color scle rnged from 1 to 8 with 1= very bright pinkish red, 4= slightly drk pinkish red, nd 8= tn to brown. Fig Lest squres mens (Lsmens) for visul color 1 of beef semimembrnosus superficil portion steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting e d c Dy of Disply b Lsmens with different superscript letters differ (P<0.05). Stndrd error = Color scle rnged from 1 to 8 with 1= very bright red, 4= slightly drk red, nd 8= tn to brown. b 38

54 Instrumentl Color Mesurements There were no lighting type by dy of disply interctions for instrumentl L* (Tble 1). Pork loin chops ws the only product to hve higher (P<0.05) L* vlue under LED lighting thn FLS lighting (Fig. 3-11). The deep portion beef semimembrnosus steks hd higher (P<0.05) * vlue t 28.5 under LED lighting in comprison to under FLS lighting. The superficil portion of semimembrnosus steks hd n interction between lighting type nd dy of disply with the d 0 LED steks hving greter * vlue thn the FLS d 0 steks (Tble 7). All other disply dy * vlues were the sme (P>0.05) regrdless of lighting type. Beef longissimus dorsi steks, ground beef, ground turkey, nd the deep nd superficil portions of beef semimembrnosus steks ll expressed decresed (P<0.05) * vlues over time. Pork loin chops displyed under LED lighting hd higher (P<0.05) b* vlues then when displyed under FLS lighting (Fig. 3-11). A lighting type by dy of disply interction occurred for b* for the deep nd superficil portions of the beef semimembrnosus steks (Tble 1). The superficil portion beef semimembrnosus steks displyed under LED lighting hd higher (P<0.05) b* vlue of on dy 0 compred to the b* vlue for the FLS smple on dy 0 while ll other vlues were similr regrdless of lighting type or dy of disply (Tble 8). The deep portion of beef semimembrnosus steks under LED lighting hd d 0 b* vlue of wheres the FLS smples hd d 0 b* vlue of with ll other vlues being similr regrdless of lighting type or dy of disply (Tble 9). Beef longissimus dorsi steks, ground beef nd ground turkey hd lower (P<0.05) b* vlues s disply time incresed. The sturtion index ws similr (P>0.05) for ll products, except beef semimembrnosus steks, under LED or FLS lighting (Tble 2). There ws n interction of lighting type nd dy of disply for the superficil nd deep portions of beef semimembrnosus steks with LED smples hving higher (P<0.05) sturtion index t compred to under FLS lighting on d 0 before becoming similr throughout the rest of disply (Tbles 10 to 11). Beef longissimus dorsi steks, ground beef nd ground turkey hd lower (P<0.05) sturtion index vlues s disply time incresed. Pork loin chops nd the superficil portion of beef semimembrnosus steks hd lower (P<0.05) /b rtio s under LED lighting (Fig. 3-12). Beef longissimus dorsi steks, ground beef nd ground turkey hd lower (P<0.05) /b rtios s disply time incresed. An interction between lighting type nd dy of disply existed where deep portion beef semimembrnosus 39

55 b* * L* Fig Lest squres mens (Lsmens) for L* 1, * 2 nd b* 3 instrumentl color vlues of five products displyed in refrigerted cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b * FLS LED * b b Top Shelf Pork Loin Chop Shelf 2 Beef Longissimus Dorsi Steks Shelf 3 Ground Beef 40 Product Shelf 4 Ground Turkey * * * Bottom Shelf Beef Semimembrnosus Superficil * Bottom Shelf Beef Semimembrnosus Deep b Lsmens within ech product hving different superscript letter differ (P<0.05). 1 L* stndrd error: Pork loin chop= 0.3, beef longissimus dorsi stek= 0.47, ground beef= 0.5, ground turkey= 0.36, beef semimembrnosus superficil= 0.36, beef semimembrnosus deep= * stndrd error: Pork loin chop= 0.21, beef longissimus dorsi stek= 0.65, ground beef= 0.54, ground turkey= 0.55, beef semimembrnosus superficil= 0.22, beef semimembrnosus deep= b* stndrd error: Pork loin chop= 0.11, beef longissimus dorsi stek= 0.42, ground beef= 0.3, ground turkey= 0.23, beef semimembrnosus superficil= 0.22, beef semimembrnosus deep= * These products hd n interction between lighting type nd dy of disply.

56 Tble 7. Lest squres mens (Lsmens) for * vlues of the superficil portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. Dy of Storge Lighting Type LED b c d d d FLS bc c d de e b Lsmens within ech column hving different superscript letter differ (P < 0.05). ce Lsmens within ech row hving different superscript letter differ (P < 0.05). Stndrd error: 0.50 Tble 8. Lest squres mens (Lsmens) for b* vlues of the superficil portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. Dy of Storge Lighting Type LED c d e e e FLS bc bc cd d d b Lsmens within ech column hving different superscript letter differ (P < 0.05). ce Lsmens within ech row hving different superscript letter differ (P < 0.05). Stndrd error: Tble 9. Lest squres mens (Lsmens) for b* vlues of the deep portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. Dy of Storge Lighting Type LED c d e ef f FLS bc c d de e b Lsmens within ech column hving different superscript letter differ (P < 0.05). cf Lsmens within ech row hving different superscript letter differ (P < 0.05). Stndrd error:

57 Tble 10. Lest squres mens (Lsmens) for sturtion index vlues of the superficil portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. Dy of Storge Lighting Type LED c d e e e FLS bc bc d d d b Lsmens within ech column hving different superscript letter differ (P < 0.05). ce Lsmens within ech row hving different superscript letter differ (P < 0.05). Stndrd error: Tble 11. Lest squres mens (Lsmens) for sturtion index vlues of the deep portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. Dy of Storge Lighting Type LED c d e f g FLS bc d e e f b Lsmens within ech column hving different superscript letter differ (P < 0.05). cg Lsmens within ech row hving different superscript letter differ (P < 0.05). Stndrd error:

58 Hue Angle /b Rtio Sturtion Index Fig Lest squres mens (Lsmens) for sturtion index 1, /b rtio 2 nd hue ngle 3 instrumentl color of five products displyed in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. 55 FLS LED 45 * * * * b b * * b b * * 35.0 Top Shelf Pork Loin Chop Shelf 2 Beef Longissimus Dorsi Steks Shelf 3 Ground Beef Product Shelf 4 Ground Turkey Bottom Shelf Beef Semimembrnosus Superficil Bottom Shelf Beef Semimembrnosus Deep b Lsmens within ech product hving different superscript letter differ (P<0.05). 1 Sturtion index stndrd error: Pork loin chop=0.22, beef longissimus dorsi stek= 0.76, ground beef= 0.59, ground turkey= 0.53, beef semimembrnosus superficil= 0.30, beef semimembrnosus deep= /b rtion stndrd error: Pork loin chop=0.01, beef longissimus dorsi stek=0.01, ground beef=0.01, ground turkey=0.02, beef semimembrnosus superficil=0.01, beef semimembrnosus deep= Hue ngle stndrd error: Pork loin chop=0.25, beef longissimus dorsi stek=0.23, ground beef=0.40, ground turkey=0.57, beef semimembrnosus superficil=0.16, beef semimembrnosus deep=0.19. * These products hd n interction between lighting type nd dy of disply. 43

59 steks under FLS lighting hd greter (P<0.05) /b rtio on d 0 compred to FLS smples on d 0 before becoming similr throughout the rest of disply (Tble 12). Pork loin chops nd the superficil portion beef semimembrnosus steks hd higher (P<0.05) hue ngles under LED lighting (Fig. 3-12). Beef longissimus dorsi steks, ground beef nd ground turkey hd higher (P<0.05) hue ngle vlues s disply time incresed. An interction between lighting type nd dy of disply existed where deep portion beef semimembrnosus steks under LED lighting hd greter (P<0.05) hue ngle vlues on d 0 compred to FLS smples before becoming similr throughout the rest of disply (Tble 13). Using instrumentl color prmeters to support the subjective comprison of visul scores cn give n indiction of shelf life extension (AMSA, 1991). Greter sturtion indices nd * vlues for the deep portion of beef semimembrnosus steks under LED lighting were indictive of extended color shelf life, but this ws not detected visully by pnelists. Conversely, color differences observed by pnelists for beef longissimus dorsi steks under LED lighting were not supported by instrumentl color mesurements. Visul differences were detected for products with greter mounts of myoglobin, nd instrumentl mesurements confirmed differences between smples held under different lighting sources with the beef semimembrnosus which hs the gretest mount of myoglobin (Bodwell & McClin, 1971; King, Shckelford, & Wheeler, 2011). The effect of LED lighting extending fresh met color life increses with incresing mounts of myoglobin. Discrepncy between the two methods of color evlution cn be ttributed to pnelists perception of color under two different lighting sources s opposed to n instrumentl mesurement using single light source. Ground beef pckged with overwrp is product tht typiclly hs short retil color life due to decresed NADH content (Ledwrd et l., 1977), res of low oxygen pressure (Kropf, 1980), nd disruption of cell membrnes with more exposed surfce to oxidtion (Govindrjn & Hultin, 1977). An extension of retil disply would reduce finncil losses for retilers. In this study, ground beef hd less visul discolortion (Fig. 3-4) under LED thn FLS lighting; however, instrumentl mesurements did not support (P>0.05) this observtion. LED lighting my help minimize visul discolortion of beef longissimus dorsi steks nd ground beef even though instrumentl dt did not support the visul pnel observtions. A study with 16 trined color pnelists conducted t the Lighting Reserch Center showed preference for retil diry products, frozen entrèes, nd beverges displyed under LED lighting compred to FLS 44

60 Tble 12. Lest squres mens (Lsmens) for /b rtio vlues of the deep portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. Dy of Storge Lighting Type LED 1.2 bc 1.18 d 1.18 d 1.12 e 1.08 e FLS 1.26 c 1.20 d 1.14 e 1.09 f 1.04 g b Lsmens within ech column hving different superscript letter differ (P < 0.05). cg Lsmens within ech row hving different superscript letter differ (P < 0.05). Stndrd error: 0.02 Tble 13. Lest squres mens (Lsmens) for hue ngle vlues of the deep portion of semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. Dys of Storge Lighting Type LED c c c d d FLS bc d e f g b Lsmens within ech column hving different superscript letter differ (P < 0.05). cg Lsmens within ech row hving different superscript letter differ (P < 0.05). Stndrd error: lighting (Rghvn & Nrendrn, 2002). They concluded tht more uniform illuminnce spectrum provided by LED lighting ws the mjor reson products displyed under LED were preferred over FLS in retil disply cses. Product Internl Temperture Product internl temperture pooled during disply under LED nd FLS lighting is shown in Fig Pork loin chops, ground beef, ground turkey nd beef semimembrnosus steks in the LED cse hd lower (P<0.05) internl tempertures thn under FLS. The internl temperture of beef longissimus dorsi steks ws similr (P>0.05) regrdless of lighting type. The lck of n internl temperture difference in beef longissimus dorsi steks displyed under LED nd FLS lighting my be due to being on disply for only 2 dys since it hd short visul color life in this study. For pork loin chops, ground turkey nd beef semimembrnosus steks, internl 45

61 product tempertures decresed (P<0.05) s dys of disply incresed regrdless of lighting type (Figs to 3-16). Temperture C Fig Lest squres mens (Lsmens) for internl temperture of five products 1 displyed in refrigerted cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. Temperture C b Top Shelf Pork Loin Chop Shelf 2 Beef Longissimus Dorsi Steks b Shelf 3 Ground Beef Product b Shelf 4 Ground Turkey FLS LED b Bottom Shelf Beef Semimembrnosus Steks b Lsmens within ech product hving different superscript letter differ (P<0.05). 1 Stndrd error: Pork loin chop = 0.04, beef longissimus dorsi stek = 0.45, ground beef = 0.45, ground turkey = 0.44, beef semimembrnosus stek = Fig Lest squres mens (Lsmens) for internl temperture of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting bc bc bc bc b c bc bc Dy of Disply b Lsmens with different superscript letters differ (P<0.05). Stndrd error =

62 Temperture C Temperture C Fig Lest squres mens (Lsmens) for internl temperture of ground turkey over 7 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b b c Dy of Disply b Lsmens with different superscript letters differ (P<0.05). Stndrd error = Fig Lest squres mens (Lsmens) for internl temperture of beef semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b b bc c Dy of Disply b Lsmens with different superscript letters differ (P<0.05). Stndrd error = Odor All products hd no off-odor on d 0 except for the beef longissimus dorsi steks tht hd very slight off-odor possibly the result of being pckged for 9 d in the cse-redy pckging in mother bg t the initition of the study. Pork loin chops displyed under FLS hd higher (P<0.05) subjective off-odor score of 2.6 versus 2.0 for chops under LED (Fig. 3-17). Off-odor 47

63 Odor Score scores for ech of the remining four products were similr within product type (P>0.05) regrdless of lighting type (Fig. 3-17). Over the durtion of the study, only beef longissimus dorsi steks nd ground beef hd odor scores of 3 equting to smll mounts of detectble odor t the end of their color life. Fig Lest squres mens (Lsmens) for subjective odor of five products 1 displyed in refrigerted cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b Top Shelf Pork Loin Chop Shelf 2 Beef Longissimus Dorsi Steks Shelf 3 Ground Beef Product Shelf 4 Ground Turkey FLS LED Bottom Shelf Beef Semimembrnosus Steks b Lsmens within ech product hving different superscript letter differ (P<0.05). 1 Stndrd error: Pork loin chop= 0.17, beef longissimus dorsi stek= 0.32, ground beef= 0.24, ground turkey= 0.71, beef semimembrnosus stek= Odor scle: 1= no off-odor, 3= smll off-odor, nd 5= extreme off-odor. Lipid Oxidtion TBARS Pork loin chops hd higher (P<0.05) TBARS vlues when displyed under LED lighting thn FLS lighting; however, the TBARS vlue remined below the threshold of consumer perceived oxidtion of ccording to Trldgis, Wtts, Younthn, & Dugn (1960) (Fig. 3-18). Beef semimembrnosus steks hd 0.24 mg mlonldehyde/kg greter (P<0.05) oxidtion under LED lighting thn FLS (Fig. 3-18). Cmpo, Nute, Hughes, Enser, Wood, & Richrdson (2006) stted tht the threshold for rncid flvor overpowering beef flvor in beef loin steks ws 2.28 mg mlonldehyde/kg TBARS vlue. Green & Cumuze (1981) determined the detectble threshold for rncid flvor in beef ws TBARS vlues between 0.6 nd 2.0 mg mlonldehyde/kg. Ground turkey under LED lighting hd higher (P<0.05) TBARS vlue of 0.31 compred to 0.25 for products displyed under FLS lighting. In ddition, there ws dy 48

64 TBARS (mg mlonldehyde/kg) effect (P<0.05) for ll five products with higher TBARS vlues t the end of disply compred to d 0, regrdless of lighting type (Figs to 3-23). Pork loin chops nd ground turkey hve greter mounts of unsturted ftty cids which re more prone to oxidtion thn sturted fts. Although some products experienced more oxidtion under the refrigerted disply cse tempertures with LED lighting, Betts nd Uri (1963) explined tht lower tempertures hold lipids in the solid phse nd provide more time for rdicls to further propgtion of oxidtion. McWeeney (1968) stted tht lipids in the solid phse hve fster rtes of lipid oxidtion thn expected. For the beef semimembrnosus steks in this study, LED lighting enhnced visul nd instrumentl color, while TBARS results showed greter oxidtion. Further reserch is needed to explore the mechnisms of lipid oxidtion under LED nd FLS lighting. Fig Lest squres mens (Lsmens) for oxidtive rncidity (TBARS) of five products 1 displyed in refrigerted cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b Top Shelf Pork Loin Chop Shelf 2 Beef Longissimus Dorsi Steks Shelf 3 Ground Beef Product b Shelf 4 Ground Turkey FLS LED b Bottom Shelf Beef Semimembrnosus Steks b Lsmens within ech product hving different superscript letter differ (P<0.05). 1 Stndrd error: Pork loin chop= 0.03, beef longissimus dorsi stek= 0.09, ground beef= 0.06, ground turkey= 0.02, beef semimembrnosus stek=

65 TBARS (mg mlonldehyde/ kg) TBARS (mg mlonldehyde/ kg) Fig Lest squres mens (Lsmens) for oxidtive rncidity (TBARS) of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b 0 8 Dy of Disply b Lsmens with different superscript letter differ (P<0.05). Stndrd error= Fig Lest squres mens (Lsmens) for oxidtive rncidity (TBARS) of beef longissimus dorsi steks over 2 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b 0 2 Dy of Disply b Lsmens with different superscript letter differ (P<0.05). Stndrd error=

66 TBARS (mg mlonldehyde/ kg) TBARS (mg mlonldehyde/ kg) Fig Lest squres mens (Lsmens) for oxidtive rncidity (TBARS) of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b 0 4 Dy of Disply b Lsmens with different superscript letter differ (P<0.05). Stndrd error= Fig Lest squres mens (Lsmens) for oxidtive rncidity (TBARS) of ground turkey over 7 dys of refrigerted in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b 0 7 Dy of Disply b Lsmens with different superscript letter differ (P<0.05). Stndrd error=

67 TBARS (mg mlonldehyde/ kg) Fig Lest squres mens (Lsmens) for oxidtive rncidity (TBARS) of beef semimembrnosus steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b 0 4 Dy of Disply b Lsmens with different superscript letter differ (P<0.05). Stndrd error= Product Microbiology Aerobic plte count nd Enterobctericee count popultions for ech smpling period nd product re shown in Fig There were no differences for APC or EB count popultions between lighting types for ground beef (Fig. 3-25). There ws n interction (P<0.05) between lighting type nd dy of disply for pork loin chops APC count popultions (Tble 3). Aerobic plte count popultions were greter (P<0.05) by more thn 2.50 log CFU/g in pork loin chops under FLS compred to LED t the end of disply thn on d 0 or t the middle of product color shelf life (Tble 14). By the end of disply, APC popultions in pork loin chops under LED were 1.91 log CFU/g lower (P<0.05) thn when displyed under FLS. As expected, APC popultions incresed (P<0.05) from d 0 to the end of disply for pork loin chops, ground beef nd ground turkey (Fig. 3-24). There ws dy effect (P<0.05) resulting in EB popultions being higher by 0.74 nd 1.56 log CFU/g, respectively for pork loin chops nd ground beef by the end of disply. There ws lighting type by dy of disply effect (P<0.05) for beef longissimus dorsi stek EB popultions where products under FLS lighting hd lower popultions by the end of disply thn product under LED (Tble 15). For ground turkey displyed under FLS, there ws lighting type 52

68 EB (log CFU/g or log CFU/cm 2 ) APC (log CFU/g or log CFU/cm 2 ) by dy of disply effect (P<0.05) resulting in the middle of color disply life EB popultions to be more thn 1.00 log CFU/g lower thn d 0 or the end of disply popultions (Tble 16). Fig Men popultions for erobic plte count (APC) nd Enterobctericee (EB) popultions cross three smpling periods 1 for five products 2 during refrigerted retil disply 3 in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting PC FLS PC LED LD FLS LD LED GB FLS GB LED GT FLS GT LED Initil Mid End PC FLS PC LED LD FLS LD LED GB FLS GB LED GT FLS GT LED 1 Initil= dy 0, Middle= middle of color disply life, End= end of color disply life. 2 PC= pork loin chop, LD= beef longissimus dorsi, GB= ground beef, GT= ground turkey. 3 Dy of end of color shelf life for ech product: PC= 8, LD= 3, GB= 4, GT= 7, SM= 4. 53

69 EB (log CFU/g or log CFU/cm 2 ) APC (log CFU/g or log CFU/cm 2 ) Fig Lest squres mens (Lsmens) for erobic plte count (APC) 1 nd Enterobctericee (EB) 2 popultions cross three smpling periods for five products 3 during refrigerted retil disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting * * FLS LED Top Shelf Pork Loin Chop * * Shelf 2 Beef Longissimus Dorsi Steks Products Shelf 3 Ground Beef * * Shelf 4 Ground Turkey b Lsmens within ech product hving different superscript letter differ (P<0.05). 1 APC stndrd error: Pork loin chop= 0.18, beef longissimus dorsi stek= 0.14 (FLS) nd 0.11 (LED), ground beef= 0.17 (FLS) nd 0.12 (LED), ground turkey= EB stndrd error: Pork loin chop= 0.19, beef longissimus dorsi stek= 0.22, ground beef= 0.34 (FLS) nd 0.31 (LED), ground turkey= 0.69 (FLS) nd 0.08 (LED). 3 Pork loin, ground beef, nd ground turkey were mesured s log CFU/g; beef longissimus dorsi steks were mesured s log CFU/cm 2. * These products hd n interction between lighting type nd dy of disply. 54

70 Tble 14. Lest squres mens (Lsmens) for Aerobic Plte Count (APC) popultions of pork loin chops in refrigerted disply cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. Dys of Storge Lighting Type Initil Mid End LED 2.94 c 3.06 c 3.64 c FLS 2.90 c 3.10 c 5.55 bd b Lsmens within ech column hving different superscript letter differ (P < 0.05). cd Lsmens within ech row hving different superscript letter differ (P < 0.05). Stndrd error: Tble 15. Lest squres mens (Lsmens) for Enterobctericee (EB) popultions of beef longissimus dorsi steks in refrigerted disply cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. Dy of Storge Lighting Type Initil Mid End LED c 0.83 bc FLS 1.65 c 0.54 c 0.17 c b Lsmens within ech column hving different superscript letter differ (P < 0.05). cd Lsmens within ech row hving different superscript letter differ (P < 0.05). Stndrd error: FLS Initil= 0.51; FLS Mid & End= 0.30; LED Mid & End= Tble 16. Lest squres mens (Lsmens) for Enterobctericee (EB) popultions of ground turkey in refrigerted disply cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting. Dy of Storge Lighting Type Initil Mid End LED 3.57 c 3.49 c 3.44 bc FLS 3.59 c 2.56 bd 3.86 c b Lsmens within ech column hving different superscript letter differ (P < 0.05). cd Lsmens within ech row hving different superscript letter differ (P < 0.05). Stndrd error: FLS Initil, Mid, End= 0.12; LED Initil= 0.17; LED Mid & End=

71 CHAPTER 4 - Conclusions Light emitting diode lighting in fresh met retil disply cses offer benefits in extending color life of pork loin chops, beef longissimus dorsi steks, ground beef, nd beef semimembrnosus steks. LED lighting extended beef retil cuts color shelf life by up to one dy longer thn under FLS. In ddition to more efficient condenser cycling, the lower opertion tempertures of LED lighting promote longer shelf life. Pork loin chops nd ground turkey color cn be displyed under LED or FLS lighting; however, if product lipid oxidtion is concern, pork loin chops nd ground turkey should be displyed under FLS lighting. Light emitting diode lighting in met retil disply cses will sve money not only by lowering fixed overhed opertionl costs but lso by extending the fresh met color life of products with greter mounts of myoglobin compred to FLS lighting. The effect of LED lighting on lipid oxidtion should be further exmined. 56

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80 b* * L* Appendix A - Figures nd Tbles Figures nd Tbles Within Appendices Fig Lest squres mens (Lsmens) for L* 1, * 2, & b* 3 instrumentl color vlues of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Dy of Disply Dy of Disply b Lsmens with different superscript letters differ (P<0.05). 1 L* stndrd error= * stndrd error= b* stndrd error=

81 Hue Angle /b Rtio Sturtion Index Fig Lest squres mens (Lsmens) for sturtion index 1, /b rtio 2, & hue ngle 3 instrumentl color of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Dy of Disply b Lsmens with different superscript letters differ (P<0.05). 1 Stndrd error = Stndrd error = Stndrd error=

82 b* * L* Fig Lest squres mens (Lsmens) for L* 1, * 2, & b* 3 instrumentl color vlues of beef longissimus dorsi steks over 2 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Dy of Disply b b Dy of Disply b Lsmens with different superscript letters differ (P<0.05). 1 Stndrd error= Stndrd error= Stndrd error=

83 Hue Angle /b Rtio Sturtion Index Fig Lest squres mens (Lsmens) for sturtion index 1, /b rtio 2, & hue ngle 3 instrumentl color of beef longissimus dorsi steks over 2 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b b c b c Dy of Disply b Lsmens with different superscript letters differ (P<0.05). 1 Stndrd error = Stndrd error = Stndrd error=

84 b* * L* Fig Lest squres mens (Lsmens) for L* 1, * 2, & b* 3 instrumentl color vlues of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting morning 0 evening 1 morning 1 evening 2 morning 3 morning 4 morning b Dy of Disply bc bcd cd e f b bc c c d e 0 morning 0 evening 1 morning 1 evening 2 morning 3 morning 4 morning Dy of Disply b Lsmens with different superscript letters differ (P<0.05). 1 L* stndrd error= * stndrd error= b* stndrd error=

85 Hue Angle /b Rtio Sturtion Index Fig Lest squres mens (Lsmens) for sturtion index 1, /b rtio 2, & hue ngle 3 instrumentl color of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b bc bcd cd 35.0 d d b b b b b b b 0 morning 0 evening 1 morning 1 evening 2 morning 3 morning 4 morning b Lsmens with different superscript letters differ (P<0.05). 1 Stndrd error= Stndrd error= Stndrd error= Dy of Disply 70

86 b* * L* Fig Lest squres mens (Lsmens) for L* 1, * 2, & b* 3 instrumentl color vlues of ground turkey over 7 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b bc c Dy of Disply b b b Dy of Disply b Lsmens with different superscript letters differ (P<0.05). 1 L* stndrd error= * stndrd error= b* stndrd error=

87 Hue Angle /b Rtio Sturtion Index Fig Lest squres mens (Lsmens) for sturtion index 1, /b rtio 2, & hue ngle 3 instrumentl color of ground turkey over 7 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b b b b b b Dy of Disply b Lsmens with different superscript letters differ (P<0.05). 1 Stndrd error = Stndrd error = Stndrd error =

88 * L* Fig Lest squres mens (Lsmens) for L* 1 & * 2 instrumentl color vlues of beef semimembrnosus deep portion steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b b b b Dy of Disply b c d e Dy of Disply b Lsmens with different superscript letters differ (P<0.05). 1 L* stndrd error = * stndrd error = b*, sturted index, /b rtio, & hue ngle ll hd significnt interction between lighting type nd dy of disply. 73

89 L* Fig Lest squres mens (Lsmens) for L* 1 instrumentl color vlues of beef semimembrnosus superficil portion steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b b b c Dy of Disply b Lsmens with different superscript letters differ (P<0.05). 1 L* stndrd error = * & b* hd significnt interction between lighting type nd dy of disply. 74

90 Hue Angle /b Rtio Sturtion Index b c c c Fig Lest squres mens (Lsmens) for /b rtio 1 & hue ngle 2 instrumentl color of 25.0 beef semimembrnosus superficil portion steks over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b b b b b Dy of Disply b Lsmens with different superscript letters differ (P<0.05). 1 Stndrd error = Stndrd error = Sturtion index hd significnt interction between lighting type nd dy of disply. 75

91 Temperture C Temperture C Fig Lest squres mens (Lsmens) for internl temperture of beef longissimus dorsi steks over 2 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Dy of Disply b Lsmens with different superscript letters differ (P<0.05). Stndrd error = Fig Lest squres mens (Lsmens) for internl temperture of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Dy of Disply b Lsmens with different superscript letters differ (P<0.05). Stndrd error =

92 APC Popultion (log CFU/g) APC (log CFU/g) Lest squres mens (Lsmens) for Aerobic Plte Count (APC) popultions of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b b Dy of Disply b Lsmens with different superscript letter differ (P<0.05). Stndrd error: Fig Lest squres mens (Lsmens) for Aerobic Plte Count (APC) popultions of beef longissimus dorsi steks over 2 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Dy of Disply b Lsmens with different superscript letter differ (P<0.05). Stndrd error: Initil= 0.23, Middle= 0.11, End=

93 APC Popultion (log CFU/g) APC Popultion (log CFU/g) Fig Lest squres mens (Lsmens) for Aerobic Plte Count (APC) popultions of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b Dy of Disply b Lsmens with different superscript letter differ (P<0.05). Stndrd error: Initil= 0.16, Middle= 0.15, End= b Fig Lest squres mens (Lsmens) for Aerobic Plte Count (APC) popultions of ground turkey over 7 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b Dy of Disply b Lsmens with different superscript letter differ (P<0.05). Stndrd error: Initil= 0.16, Middle= 0.16, End= b 78

94 EB Popultion (log CFU/g) EB Popultion (log CFU/g) Fig Lest squres mens (Lsmens) for Enterobctericee (EB) popultions of pork loin chops over 8 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting Dy of Disply b Lsmens with different superscript letter differ (P<0.05). Stndrd error= b Fig Lest squres mens (Lsmens) for Enterobctericee (EB) popultions of ground beef over 4 dys of refrigerted disply in cses equipped with fluorescent (FLS) or light emitting diode (LED) lighting b Dy of Disply b Lsmens with different superscript letter differ (P<0.05). Stndrd error: Initil= 0.36, Middle= 0.36, End= b 79

95 Appendix B - Cse Specifictions nd Visul Color Anlysis UV, correlted color tempertures nd lumens for fluorescent (FLS) nd light emitting diode (LED) lighting. 1, Top shelf , Bottom 1, Top Shelf , Bottom FLS Cse Ave. Lux uv uv uv uv uv 3174 K 3179 K 3170 K 3180 K 3144 K uv uv uv uv uv 3232 K 3248 K 3215 K 3252 K 3210 K uv uv uv uv uv 3240 K 3259 K 3251 K 3300 K 3219 K uv uv uv uv uv 3276 K 3258 K 3229 K 3295 K 3253 K uv uv uv uv uv 3389 K 3339 K 3303 K 3362 K 3328 K LED Cse ( ) uv ( ) uv ( ) uv ( ) uv ( ) uv 3045 K 3025 K 3026 K 3021 K 2949 K ( ) uv ( ) uv ( ) uv ( ) uv ( ) uv 2965 K 2934 K 2941 K 2940 K 2888 K ( ) uv ( ) uv ( ) uv ( ) uv ( ) uv 2994 K 3050 K 3036 K 3077 K 3038 K ( ) uv ( ) uv ( ) uv ( ) uv ( ) uv 2979 K 2991 K 3029 K 3105 K 3060 K uv uv uv uv uv 3676 K 3559 K 3551 K 3626 K 3600 K

96 Fig Five fresh met products displyed in retil disply cses outfitted with fluorescent or light emitting diode lighting. (Photo courtesy of Dr. Melvin Hunt). 81

97 82 Fig Product lyout within ech disply cse. Study Design LED vs. FLS Lighting Comprison in M5X Cses Top Shelf 1 Row 2 Pork Pork Pork Pork Pork Pork Pork Pork Pork Pork Pork Pork Shelf 1 Row 1 Pork Pork Pork Pork Pork Pork Pork Pork Pork Pork Pork Pork Shelf 2 Row 3 LD LD LD LD LD LD LD LD LD LD LD LD Shelf 2 Row 2 LD LD LD LD LD LD LD LD LD LD LD LD Shelf 2 Row 1 LD LD LD LD LD LD LD LD LD LD LD LD Shelf 3 Row 2 GB GB GB GB GB GB GB GB GB GB GB GB Shelf 3 Row 1 GB GB GB GB GB GB GB GB GB GB GB GB Shelf 4 Row 2 GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP Shelf 4 Row 1 GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP GT MAP Shelf 5 Row 3 SM SM SM SM SM SM SM SM SM SM SM SM Shelf 5 Row 2 SM SM SM SM SM SM SM SM SM SM SM SM Shelf 5 Row 1 SM SM SM SM SM SM SM SM SM SM SM SM Replicte 1 Replicte 2 Replicte 3 Replicte 4 Replicte 5 Replicte 6

98 Fig Superficil nd deep portion of the beef semimembrnosus. Superficil Portion Semimembrnosus Ignore Deep Portion 83