The effects of UV-C treatment on the quality of orange, carrot and celery juice blend

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1 Review Article The effects of UV-C tretment on the qulity of ornge, crrot nd celery juice blend Nik Nornis, Chndrn Somsundrm*, Zulin Rzli Biotechnology Division, Institute of Biologicl Sciences, University of Mly, Mlysi Abstrct Juice blend is first becoming the preferred choice of beverge due to it high nutritionl qulity. However, current methods tht re used in the processing of juice products, such s therml tretments, hs been reported significntly reduces nutritionl qulity. UV-C tretment is n lterntive method tht could extend the shelf life s well s mintin the qulity of juice. In this study, the qulity ttributes of the juice blend upon exposure to ultrviolet light nd therml tretment were studied. Freshly squeezed ornge, crrot nd celery juice blend ws exposed to ultrviolet light (for 15, 30, nd 60 minutes) nd therml psteuriztion (t 90 C, for 30 s nd 60 s). Microbil nlysis, physicochemicl properties, ntioxidnt ctivity s well s other qulity prmeters were crried out on ll smples. The results showed no significnt difference in physicochemicl properties mong ll smples studied. Nevertheless, significnt increse ws observed in polyphenol content, ntioxidnt cpcity, nd flvonoid content in smples treted with UV-C compred to control nd therml treted. Moreover, juice blend exposed to UV-C tretment (30 nd 60 minutes) showed increse in extrctbility of crotenoids. UV-C treted smples lso exhibited reduction in microbil lod nd prolonged shelf life. The results obtined support the use of UV-C s n lterntive to therml tretment in improving the qulity of juice blend. Keywords: UV-C tretment, Nutritious food, Psteuriztion, Spoilge enzymes. Accepted on October 08, 2018 Introduction Higher demnd from consumers for functionl nd nutritious food hs led to the processing of mixed fruit nd vegetble juices, otherwise known s juice blend [1]. The consumption of juice blend hs been ssocited with higher nutrient nd fibre intke s well s ntioxidnt nd nti-inflmmtory properties [2]. One of the most populr juices is mix of crrot nd ornge minly becuse of its ttrctive colour nd blnced tste. Celery s stnd-lone vegetble is the most extensively consumed vegetble vilble in the mrket nd is pprecited s it is n excellent source of nutrition especilly Vitmin K nd molybdenum [3]. The ddition of celery into crrot nd ornge juice blends increses totl nutrition nd helps improve pltbility s the flvour from ornge nd crrot helps diminish the bitter tste of celery. Currently, therml psteuriztion is the most preferred method for processing food due to its bility to inctivte microorgnisms nd food spoilge enzymes, therefore extending the shelf life of juices [4]. However, due to high het exposure, therml tretment cn negtively ffect the food product qulity, cusing severl chemicl nd physicl chnges which lowers the biovilbility of some bioctive compounds such s scorbic cid [4-6]. Nontherml processing hs been explored for its efficcy to extend shelf life nd enhnce sfety of fresh juice while preserving nutritionl qulities. UV-C light with pek emission t 254 nm exhibits germicidl effect ginst microorgnisms such s bcteri, viruses, yests nd moulds [7]. Furthermore, contrry to het tretments, the use of UV-C hs been reported to cuse 1 miniml dmge to the physicochemicl nd nutritionl qulity of juice [8]. This study ims to compre the qulity of therml nd UV-C treted juice blend. Anlysis will include shelf life studies s well s physicochemicl nd ntioxidnt nlysis. Mterils nd Methods Preprtion of juice blend Ornge, crrot nd celery, free from externl defects were purchsed from locl supermrket in Kul Lumpur, Mlysi. Fruits nd vegetbles were wshed with sterile distilled wter. Wshed fruits nd vegetble were cut nd where necessry, seeds were discrded. All cut fruits nd vegetbles were blended using household juice blender (Philips Juice Extrctor HR 2820). Ech extrcted juice ws then filtered using plstic sieve with dimeter of 2 mm to remove ny remining pulp or fibre. The filtered ornge, crrot nd celery juice were mixed with rtio of 1:1:0.1. For comprtive purposes, n untreted smple ws similrly retined nd ssyed. Therml tretment nd UV-C tretment The juice blend ws heted in wter bth (Memmert, Germny) t 90 C for 30 s (mild het psteuriztion) nd 60s (high het psteuriztion). The temperture of the juice smples were regulrly monitored t the centre of the boiling tube using thermometer. The mesurement time ws tken when the juice smples reched the trget temperture. After therml tretment, the juice smples were cooled down by immersing in n ice wter bth. The juice smples were exposed to UV-C light under btch conditions. The juice smple ws poured into

2 Cittion: Nornis N, Somsundrm C, Rzli Z. The effects of UV-C tretment on the qulity of ornge, crrot nd celery juice blend. J Food Sci Nutr. 2018;1(3):1-7. sterile Petri dishes nd then exposed to germicidl UV-C light in lminr flow cbinet (Gelmn Science Biologicl Sfety Cbinet Clss II, NSW, Austrli). The durtion of exposure of UV-C light ws 15, 30 nd 60 minutes. The following terms were used to describe the different tretments in this study: control (untreted smple); T30 (therml tretment for 30 seconds); T60 (therml tretment for 60 seconds); UV15 (UV- C tretment for 15 minutes); UV30 (UV-C tretment for 30 minutes); UV60 (UV-C tretment for 60 minutes). Microbil inctivtion nlysis Control, therml treted, nd UV-C treted juice blend were filled into sterile glss bottles. The bottles were cpped tightly nd stored in fridge t 4 ± 1 C for 13 dys. Microbil count of juice blend smples ws nlysed right fter tretment (dy 0) nd fter storge for 13 dys. The microbil count for juice smples were determined using 3M Petrifilm pltes (3M Centre, MN, USA) for erobic bcteri ccording to the method by Snthirsegrm, et l. [9]. The erobic bcteri were clculted s colony forming units (CFU) per millilitre of juice using the following eqution: ( number of colonies x dilution fctor of plte) CFU / ml = liquot plted Physicochemicl nlysis (ph, totl soluble solids nd titrtble cidity) The ph of the juice smples ws determined using ph meter (Hnn Microprocessor ph 211, Itly). Totl soluble solids were determined using digitl refrctometer (Atgo PR-1 digitl refrctometer). Results were expressed in stndrd Brix unit. Determintion of titrtble cidity ws crried out ccording to the method by Sdler & Murphy, (2010). The titrtble cidity ws clculted using the following formul: V1 x 0.1 N NOH x eq. of wt. in cid X 100 %TA = V2 x 1000 Where V1 is volume of titrnt (ml), Eq. of wt. in cid is equivlent of weight of nhydrous citric cid (64 mg/meq) nd V2 is volume of smple (ml). Clrity nd non-enzymtic browning index (NEBI) The clrity of juice ws determined by mesuring the trnsmittnce of superntnt t 660 nm using spectrophotometer, bsed on the method by Glevitzky, et l. [10]. High percentge of trnsmittnce t 660 nm corresponds to high clrity. NEBI ws crried out bsed on the method by Cohen, et l. [11]. Ascorbic cid content The scorbic cid content in juice smples ws determined using the 2,6-dichlorophenol-indophenol (DCPIP) visul titrtion method by Rngnn [12]. Diluted juice smple ws filtered using Whtmn No.1 filter pper. Then, the filtrte ws titrted with stndrdized dye solution to pink end point. Results obtined were expressed s milligrm of scorbic cid per 100 ml of smple, using the following eqution: V1 x dye fctor x V2 x 100 Ascorbic cid content = S1 x S2 Where V1 is titre (ml), V2 is volume mde up (ml), S1 is liquot of extrct tken for estimtion (ml), nd S2 is volume of smple tken for estimtion (ml) Totl crotenoid content Crotenoid ws extrcted using the method by Lee, et l. [13]. The totl crotenoid content ws determined ccording to Scott [14]. Absorbnce of extrcted hexne ws mesured t 450 nm. The totl crotenoid content using β-crotene s reference ws clculted using the following formul: Totl crotenoid content=(a V 1 C 1% )/(A 1% ) Where A is bsorbnce reding of the diluted smple, V 1 is dilution fctor, A 1% is bsorbnce of 1% solution (the extinction coefficient for β-crotene: 2592 AU), nd C 1% is concentrtion of 1% solution (10 mg/ml). Antioxidnt ctivity Preprtion of extrct: The ntioxidnt extrction ws performed bsed on Xu, et l. with slight modifictions [15]. Juice blend smple ws dded to 80% methnol with rtio of 1:1 to purify the smple. The mixture ws plced in rotry shker (Orbitl Shker S01, Sturt) for 30 minutes t room temperture, nd then centrifuged (UEC Micro). The superntnt ws used for ntioxidnt nlysis. Totl polyphenol content (TPC): Totl polyphenol content of juice smples ws determined using Folin-Cioclteu ssy modified to microscle [16]. A stndrd curve of gllic cid (y= x, r 2 =0.9955) ws prepred, nd the results were expressed s milligrms of gllic cid equivlent (GAE) per 100 ml of juice smples. 1,1-Di-phenyl-2-picrylhydrzyl (DPPH) rdicl scvenging ssy: DPPH ssy ws crried out bsed on the method by Be nd Suh [16]. A stndrd curve of scorbic cid (y=10.145x, r 2 =0.9907) ws prepred nd results were reported s microgrms of scorbic cid equivlent (AAE) per ml juice extrct. The rdicl scvenging ctivity ws then clculted using following eqution: % DPPH Inhibition=(A control A smple /A control ) 100 Where A control =bsorbnce reding of control nd A smple =bsorbnce reding of smple Totl ntioxidnt cpcity (TAC): Totl ntioxidnt ctivity in juice smples ws determined bsed on phosphomolybdenum method by Prieto, et l. [17]. A stndrd curve of scorbic cid (y=0.0018x, r 2 =0.9981) ws prepred nd the results were reported s microgrms of scorbic cid equivlent (AAE) per ml juice extrct. Totl flvonoid content (TFC): The totl flvonoid content ws determined bsed on the colorimetric method described by Sknk, et l. [18]. A stndrd curve of ctechin (y=0.0135x, r 2 =0.9943) ws prepred. Results were reported s milligrms of ctechin equivlent (CE) per 100 ml juice smple. Sensory nlysis Consumer s cceptnce test ws crried out t lbortory 2

3 Nornis/Somsundrm/Rzli (University of Mly) by 30 untrined pnellists. Six bottles of smples were prepred nd lbelled rndomly s A, B C, D, E, nd F. Ech pnellist ws given plstic spoon to tste the smples. Wter nd crckers were served for clensing the plte between smples. Pnellists evluted ppernce, odour, flvour, sweetness, cidity nd overll cceptbility using 1-5 scle, with 1 corresponding to much dislike nd 5 to like lot. Sttisticl nlysis All dt ws subjected to sttisticl nlysis using SPSS Softwre (SPSS Inc, IBM). The experimentl tretments were compred using one-wy nlysis of vrince. Significnt differences (p<0.05) between tretment mens were determined by Tukey s HSD (Honestly Significnt Difference) test. Results nd Discussion Microbil inctivtion nlysis (erobic plte count) The shelf life of juice smples ws evluted ccording to the Institute of Food Science nd Technology, IFST (1999). The cceptble mximum microbil lod in fruit juices is 4 log CFU/ ml. The erobic bcteri count in freshly squeezed juice blend ws 3.42 log CFU/ml, while therml treted nd UV-C treted smples showed no colony counts (Tble 1). Both tretments successfully reduced erobic bcteri counts to below detection limits with UV60 exhibiting the most effective microbil lod reduction mong UV tretments. After dy 7, untreted juice exceeded the cceptble microbil lod. On the contrry, ll treted smples mintined microbil lod below 4 log CFU/ml throughout 13 dys of storge with T60 nd UV60 recording the lowest count. This could be consequence of the denturtion of orgnic molecules necessry for proper functioning of microbil cells by high temperture, thus cusing cellulr deth while bsorption of UV-C by microbil DNA or RNA structures results in the formtion of pyrimidine dimers which stops microorgnisms from replicting, thus inctivting microbil growth [1]. Nevertheless, shorter exposure to UV-C ws not s efficient in eliminting microbil growth s erobic count ws detected by dy 7. Our results re consistent with other findings where longer exposure to UV-C resulted in greter reduction of microbil lod [8]. Physicochemicl nlysis (ph, TSS, nd TA) No significnt difference in ph ws observed in smples fter tretment s well s fter storge for 7 dys (Tble 2). This is greeble with studies by Bull, et l. nd Pl nd Toklucu, who observed no significnt ltertions in ph of juice processed with het psteuriztion [5,19]. A slight decrese in ph fter storge my result from orgnic cids relesed due to brekdown of dissolved prticultes. In contrst, significnt difference in TSS ws observed in ll treted smples compred to control, except UV15. Similr to the findings of Chi, et l. [20], the TSS vlue of UV-C rdited juice ws lower thn het psteurized juice throughout storge for 13 weeks. The sme trend ws lso observed in titrtble cidity (TA), where UV-C treted juice showed lower TA vlue compred to therml psteurized juice throughout storge for 7 dys. The chnges in TSS nd TA my be explined by the presence of microorgnism in juices tht cuse deteriortion of fruit juice s result of sugr fermenttion [21]. Clrity nd NEBI Clrity cts s n indictor for turbidity level or drkening of fruit juices. Therml treted smples showed the lowest clrity with 48% reduction compred to control (Tble 3). When het is pplied to juice smples, the juice prticle becomes lrger nd colloidl mterils will consequently clot [22,23], which will then contribute to the incresing viscosity of juice. In ddition, high viscosity of juice my lso be contributed by the swelling of prticles nd infiltrtion of wter between cellulose chins during heting process [23]. Furthermore, during therml psteuriztion of juices, cell wll is gretly ruptured which leds to lekge of soluble pectin out from the cell wlls. This leds to highly concentrted pectin colloidl solution [24,25]. Incresed viscosity nd pectin concentrtion contributes to decrese of Tble 1. Effects of therml tretment nd UV-C tretment on erobic bcteri count of juice blend. Tretment Log of Colony Forming Units per ml of juice (CFU/ml) Dy 0 Dy 7 Dy 13 Control 3.42 ± b 3.96 ± > 4.00 T30 ND ND b 3.56 ± cd T60 ND ND b 3.20 ± bc UV15 ND 3.46 ± ± e UV30 ND 3.00 ± b 3.75 ± de UV60 ND ND b 3.36 ± bc Tble 2. Effects of therml tretment nd UV-C tretment on physicochemicl properties (ph, totl soluble solids nd titrtble cidity) of juice blend. Smples ph TSS TA DAY 0 DAY 7 DAY 0 DAY 7 DAY 0 DAY 7 Control 3.88 ± ± ± ± bc 0.48 ± b 0.37 ± b T ± ± ± c 9.23 ± c 0.41 ± ± b T ± ± ± bc 8.93 ± bc 0.39 ± ± b UV ± ± ± b 8.6 ± b 0.44 ± b 0.37 ± UV ± ± ± bc 8.4 ± b 0.4 ± ± UV ± ± ± bc 8.3 ± ± ±

4 Cittion: Nornis N, Somsundrm C, Rzli Z. The effects of UV-C tretment on the qulity of ornge, crrot nd celery juice blend. J Food Sci Nutr. 2018;1(3):1-7. Tble 3. Effects of therml tretment nd UV-C tretment on clrity nd non-enzymtic browning index of juice blend. Smples Clrity NEBI DAY 0 DAY 7 DAY 0 DAY 7 Control 1.4 ± b 1.6 ± b ± ± T ± ± ± b ± c T ± ± ± b ± b UV ± b 8.07 ± c ± ± UV ± b 7.57 ± c ± ± UV ± b 7.8 ± c ± b ± Tble 4. Effects of therml tretment nd UV-C tretment on crotenoid content nd scorbic cid content of juice blend. Smples Totl crotenoid content (mg/ml) Ascorbic cid content (mg/100 ml) DAY 0 DAY 7 DAY 0 DAY 7 Control 0.31 ± 0.01 b 0.44 ± ± 6.73 b ± 3.37 T ± 0.02 c 0.27 ± ± 7.14 b ± 8.91 T ± 0.03 bc 0.43 ± ± 3.37 b ± 5.83 UV ± ± ± 5.83 b ± 3.37 UV ± 0.02 bc 0.38 ± ± 3.37 b ± 6.73 UV ± ± ± ± 3.57 clrity in therml treted juice smples. Clrity of juice smples treted with UV-C exhibited no significnt chnges. This is greeble to the work done by Shmsudin, et l. [26], where pinepple juice processed with UV-C exhibited no chnges in prticle size, thus clotting of colloidl mterils were voided, leding to unchnged viscosity of UV-C processed juice. A significnt increse in NEBI ws observed in therml treted smples while smples treted with UV-C showed no-significnt increse. NEBI is n indictor of the browning of juice due to Millrd rection, consequently leding to chnges in colour nd nutrient loss [7]. Non-enzymtic browning is usully initited t high temperture conditions. These conditions ccelerte brown pigment formtion, thus drkening the juice. A study by Aguilo-Aguyo, et l. [27] showed significnt browning in therml psteurized strwberry juice. Noci, et l. reported lrge difference in NEBI vlues in therml treted juice while UV-C treted smples exhibited minor differences reltive to untreted juice [28]. This suggests the bility of UV processing to retin similr chrcteristics with untreted juice. Totl crotenoid content UV-C treted smples showed n increse in crotenoid content (Tble 4), with UV30 exhibiting n enhncement of 84% of crotenoid extrcted, nd n enhncement of 3% for UV60. This shows tht crotenoids were still stble fter 30 nd 60 minutes of exposure to UV-C. An improvement of crotenoid extrction my be due to the inctivtion of enzymes (cused by ltertion of DNA by UV photons) responsible for crotenoid degrdtions [10]. After storge for 7 dys, the highest increse (35%) in crotenoids extrcted ws observed in UV15 smple, while therml treted smples exhibited reduction in crotenoid content. Certin types (or isomers) of crotenoid my be differently ffected by storge time. According to Chen, et l. the concentrtion of crotenoid (13-cis-lutein) incresed during storge for 3 months [29]. However, decrese in totl crotenoid content ws shown in untreted blend of fruit juicesoymilk s storge time incresed [30]. Control hd significntly higher crotenoid content compred to both therml nd UV-C treted juice smple, which could be result of the het nd light sensitive chrcteristics of crotenoid [31,32]. Ascorbic cid content After both tretments, significnt reduction of scorbic cid content ws shown in juice smples in comprison with control (Tble 4). UV15 smple exhibited the lest reduction of scorbic cid content (44%) wheres T60 smple showed the highest reduction (53%). Ascorbic cid is lightsensitive compound nd is importnt in fresh juices due to its ntioxidnt bility. Ascorbic cid content ws gretly reduced upon therml psteuriztion, s it is thermolbile bioctive compound [33]. Bsed on previous study, high temperture ws found to highly ffect scorbic cid degrdtion through n erobic pthwy [34]. Similrly, Pl nd Toklucu observed significnt degrdtion of scorbic cid in therml psteurized ornge juice, due to its het sensitive chrcteristics [35]. The loss of scorbic cid fter UV-C processing is considered norml due to its chrcteristics tht is the strongest bsorber of UV-C light [1]. However, juice processed with UV-C retined higher mount of scorbic cid compred to het psteurized juice throughout storge period. Enhncement in ntioxidnt ctivity including scorbic cid content my occur in UV-C treted juice, s observed in Golden Delicious pples exposed to UV-C which contin higher scorbic cid content compred to untreted smples fter storge for 30 dys (Lee nd Cotes, 2003). Antioxidnt ctivity (TPC, TFC, TAC, nd DPPH rdicl scvenging ctivity ssy) The effects of therml nd UV-C tretment on ntioxidnt ctivity of juice blend re shown in Tble 5. A significnt enhncement in extrctbility of phenolic compounds by UV-C tretment ws observed, where UV30 (50.43 mg GAE/100 ml) exhibited the highest mount of phenolic compounds extrcted compred to control (31.23 mg GAE/100 ml). Exposure of UV-C my contribute to increse enzyme phenyllnine lyse ctivity, which then contributes to ctivtion of phenolic 4

5 Nornis/Somsundrm/Rzli Tble 5. Effects of therml tretment nd UV-C tretment on totl polyphenol content, DPPH rdicl scvenging ctivity, totl ntioxidnt cpcity nd totl flvonoid content of juice blend. Smples TPC (mg GAE/100 ml) DPPH (µg AAE/ml) TAC (µg AAE/ml) TFC (mg CE/100ml) DAY 0 DAY 7 DAY 0 DAY 7 DAY 0 DAY 7 DAY 0 DAY 7 Control ± ± ± ± ± ± 8.15 b 1.21 ± ± 0.80 T ± 3.48 bc ± ± ± ± 5.00 b ± 5.46 c 1.05 ± ± 0.29 T ± 1.21 b ± ± 1.63 b ± ± ± d 1.06 ± ± 0.09 UV ± 1.31 bcd ± ± ± 0.11 b ± ± ± ± 0.32 UV ± 3.93 d ± ± ± ± ± ± ± 0.71 UV ± 4.17 cd ± ± ± ± ± ± ± Sensory Anlysis No. of respondents g h gh b e i f c gh i f b b d i gh hi hi f g e e e c Much disliked Disliked Moderte Liked Liked lot 0 Control T30 T60 UV15 UV30 UV60 Smple Figure 1. Effects of therml tretment nd UV-C tretment on sensory evlution of juice blend. biosynthesis pthwy, thus leding to enhncement of phenolic compounds [36]. Further degrdtion of polyphenols is voided s UV-C promotes inctivtion of polyphenol oxidse [1]. On the other hnd, therml tretment lso resulted in n increse in totl phenolic content, T30 (25.6%) nd T60 (15%). The totl polyphenol content in ll treted smples showed no significnt difference fter storge. This is similr to study conducted by Goh. et l. tht observed no significnt difference in totl polyphenol content of pinepple juice treted with therml nd UV-C fter storge for 2 weeks [37]. The enzyme tht degrdes phenolic compound, peroxidse, were inctivted thus mintining the phenolic compound throughout storge [33]. A similr trend ws observed in the totl ntioxidnt cpcity of treted smples. Except for T30 on dy 0, ll treted smples exhibited n increse in TAC fter storge. The increse in ntioxidnt cpcity my be due to increse of polyphenolic compounds in the juice blend s result of enzyme ctivtion s discussed erlier. Nevertheless, fter storge the DPPH ctivity in T30 incresed to be similr to the control. No significnt chnges were observed in totl flvonoid content of ll smples fter tretment nd fter storge. In contrst, n increse in flvonoid hs been reported fter UV-C tretment. This could be defensive response to the development of free rdicls, which is triggered by UV-C light exposure which subsequently initites the ccumultion of phytolexins nd other stress responses [36]. Sensory nlysis Control ws positioned in moderte scle, while liked nd liked lot scle were observed higher in UV-C treted smples compred to therml treted smples (Figure 1). Therml tretment ws lso positioned in moderte scle, with T60 obtining highest disliked rte. From the results, T60 smple flls in the highest disliked scle. This is similr to Sentndreu, et l. who reported decrese in tste of fruit juice heted bove 70 C [38]. On the other hnd, UV-C treted smples obtined higher score for liked nd liked lot scle. Overll, juice blend treted with UV-C exhibited no significnt chnges in tste nd ws ccepted by most pnellists. Conclusions Both therml tretment nd UV-C tretment successfully extended the shelf life of juice blend. However, therml tretment resulted in poorer visul qulity where clrity ws compromised s well s significnt reduction in crotenoid nd scorbic cid, both which re importnt nutritionl chrcteristics of juice. Furthermore, therml treted juice ws lest ccepted by consumers compred to control nd UV-treted smples. UV-C on the other hnd hd better retention of physicochemicl nd nutritionl qulity nd received the highest preference by consumers. As conclusion, ll results showed the potentil use of UV-C in extending shelf life of juice blend s well s mintining the qulity of juice blend. Acknowledgements The uthors would like to thnk the CEBAR RU grnt for supporting this reserch. 5

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