Mature Fruit Vegetables Tomatoes Peppers, Chiles Marita Cantwell, UC Davis micantwell@ucdavis.edu Maturity at harvest critical for quality Chilling sensitive, but variable in sensitivity Ethylene can control ripening Moderate respiration rates; can be stored Postharvest Technology Short Course June Ch. Postharvest Technology Book Tomato Quality Attributes Size, shape Condition no damage no decay Texture Firmness, mealiness, juiciness, slice integrity Color Red color and lycopene content Flavor and Composition Sugars Acids Aroma volatiles Vitamins Maturity & Ripening Stages GREEN The tomato surface is completely green. The shade of green may vary from light to dark. Tomato mature-green & breaker stages PROBLEMATIC! Immature MG MG MG Br VR BREAKERS There is a definite break of color from green to bruised fruit Tannish-yellow, pink or red or or less of the tomato surface. TURNING Tannish-yellow, pink or red color shows on over but not more than of the tomato surface. PINK Pink or red color shows on over but not more than of the tomato surface. LIGHT RED Pinkish-red or red color shows on over but red color covers not more than of the tomato surface RED Red means that more than of the tomato surface, in aggregate, is red http://www.tomato.org/ http://www.floridatomatoes.org/ Relative Value MG Breaker Turning Pink Light Red Red Respiration Ethylene Time Red color Yellow color Aroma Flavor Sugars Soluble pectins Polymerized phenolics Green color Acidity Starch Flesh firmness Insoluble pectins Simple phenolics Tomato photos: http://www.tomato.org/food/color.html µl CO /g-h nl C H /g-h Respiration Ethylene Production T T Trin at C from Breaker stage Trin x T Ripening mutants retard the ripening process Example: Tomato rin mutant
Firmness Classes for Tomatoes Firmness Class Description Firmness Newtons force to compress mm Very firm yields slightly to considerable finger pressure - Firm yields slightly to moderate finger pressure - Moderately firm -- - Moderately soft yields readily to moderate finger - pressure Soft yields to slight finger pressure Very soft yields very readily to slight finger Other Textural Characteristics pressure Slice Integrity Newton =. kg-force or. pound-force Mealiness Tomato Color Carotenoids and other carotenes Lycopene () Pigment extraction, Objective color values Typical Objective Color Values for Tomatoes L* a* b* chroma hue Hue Lycopene..... Pink-Orange Orange-Red Red Dark Red.................... Lycopene in the pericarp, mg/kg FW Flavor and Sugar:Acid Ratio ACIDS Low Moderate to High Low Insipid, tasteless Sour, tart SUGARS High Sweet Best flavor combination Tomato Flavor Depends on content of: Sugars (-) Acids (.-.) Aroma volatiles (ppm) Soluble solids measured by a refractometer = sugars, but also organic acids, soluble pectins, anthocyanins, phenolic compounds, ascorbic acid We estimate flavor by measuring sugars (soluble solids) and acids (titratable acidity)
Tomato Type & Composition, U.S. Retail Tomato Type Soluble Solids Titratable Acidity Grape.. Cherry.. Orange Cluster.. Round.. Roma.. Round Cluster Soluble. Titratable. Tomato Type Solids Acidity Cherry.. Campari.. Romanita.. Grape.. Round greenhouse.. Group Group Composition of Ripe Grape Tomato Harvested at Stages of Maturity Initial Maturity Stage Weight fruit, g Red color, hue Firmness, N force Soluble solids, Sugars mg/ml Titratable acidity, Vitamin C mg/ml............... LSD.. ns... ns Minimum harvest stage should be Stage (pink-orange) Average cvs, Cantwell, At Packhouse Checker boarding Should never be a problem with vine ripe tomatoes! Quality of ripe greenhouse TOV tomatoes of two cultivars. Fruit were stored at.c for days. Fruit are numbered from to in order of ripening. Only trusses with all red fruit after days were evaluated (Cantwell, ). Cultivar Fruit no Weight g Color (hue) Firmness N Soluble solids Titratable acidity Espedella......................... Success......................... At Distribution LSD...... Storage of Tomatoes. C ( F) No lower than C ( F) - weeks Controlled atmospheres O, < CO Relative humidity ~ Avoid chilling temperatures for tomatoes F C Too low temperature (< C < F) Reduces flavor Affects ability to ripen Increases decay
z--hexanal, ppm Low temperatures reduce aroma volatiles z- hexanal as example of important volatile Table-ripe tomatoes stored for days.... More recent research shows that C is too low for good aroma profile Cv Bobcat Initial Color Stage = Stored days. C. C. C. C = F. C = F. C = F It is quite common that tomatoes are held at F. Results in decay and poor color. Storage temperature, ºC Cantwell, UC Davis, unpublished C C Color Changes during storage and after transfer to C at, and days = full red Color Changes during storage and after transfer to C at, and days = full red Color score C ( F). C ( F) C ( F) C ( F) Color score C ( F). C ( F) C ( F) C ( F) Cv Bobcat, round field-grown variety Ara and Cantwell Cv Bobcat Ara and Cantwell A. Red color, Hue Round Tomato (cv Bobcat) stored weeks + days Hue color value Storage Temperature. C ( F) C ( F).C C ( F) C ( F) LSD. Lower the hue value, redder the fruit Initial Most of the fruit stored longer than week at and. C ( and F) had decay and did not ripen. Initial stage = C ( F). C ( F) C ( F) Lycopene, mg/kg FW B. Lycopene Storage Temperature. C ( F) C ( F).C C ( F) C ( F) LSD. Fruit stored at C and. C that did not decay, lacked the ability to develop red color. Weeks storage
Storage for grape tomatoes is somewhat different due to water loss; High quality grape tomatoes on salad trays at C okay for - days A. Visual Quality B. Weight Loss C d C d =excellent, =unuseable LSD. percent C ( F) C ( F) C ( F) C ( F) C. Firmness D. Red color Visual quality of packaged grape tomatoes after days. Newtons-force Hue color value C d Grape Tomatoes (cv Amsterdam) stored in consumer packaging at temperatures. Cantwell, unpublished,. Shelf-life/Storage/Ripening Conditions Temperature and ripening of different tomato types; update conventional tomato chart Impact of lower than recommended storage temperature; slight chilling; differences among varieties Ripening Temperature and ethylene treatment Temperature and RH -Impact on firmness and gloss Table. Effect of temperature on ripening rates of conventional tomatoes. Ripeness stage to full red color at indicated temperature.c F C F.C F C F.C F C F Maturegreen Breaker Turning Pink Color score Ethylene production (nl.g-h) Respiration (µl CO.g-h) =green, =table-ripe A. Respiration C ( F) C ( F) cv Bobcat average fruits initial stage = (MG) B. Ethylene production C. Red color Final C C Hue (Red color).. N firmness.. soluble solids.. acidity.. Tomato Ripening & Temperature C allows ripening to continue but at much slower rate than at C Similar to ripening bananas and other fruits Tomatoes ripen into similar quality in temperature range from.- C Temp. C Initial color to TR Weight loss Firmness N Red color Hue SS Sugar mg/ml TA Vit. C mg/ml............... Respiration µl CO. g - h - A. Respiration. C ( F) C ( F) C ( F) Impact of Temperature on Tomato Ripening Respiration, Ethylene and Color Avoid Ripening above C.............................. Ethylene production nl. g - h - B. Ethylene production............... Average C....... Average.C....... LSD...... ns. Color Score (=green, =table-ripe) C. Color change Cv Mature-green Mountain Fresh Fruit Cantwell, #, unpublished; cv Bobcat - from Breaker Stage
Tomatoes and -MCP (SmartFresh ) cv Bobcat days at C Treated h with -MCP at Breaker stage ppb -MCP at C ~. C Storage -MCP is a powerful regulator of tomato fruit ripening Easy to overdose and have poor final quality (red fruit) Important to determine where -MCP can add value to the tomato category Review Paper: The use of -MCP on fruits and vegetables. C.B. Watkins.. Postharvest Biology Technology : -. ppb ppb ppb cv Bobcat days from Breaker stage. C C C Ethylene Treatment for Ripening MG fruit Ethylene concentration: - ppm Temperature: - C ( to F) Relative humidity: - Duration: to hours Air circulation: sufficient for distribution of ethylene in ripening room Ventilation: sufficient to prevent accumulation of CO which reduces effectiveness of ethylene
Checker boarding Vine-ripe Greenhouse Tomato At Packhouse Should never be a problem with vine ripe tomatoes! Why did they have variability? What changes did they make? At Distribution Sensory Evaluation Project Fruit with decay and other defects. Tomato type MG ripened Field-grown Pinks Field-grown Number fruit evaluated decay defects VR field Hothouse MG field TOV Type of defect.. Poor color, sunburn, too soft.. Poor color, excessively soft Hothouse.. Shrivel, mechanical damage TOV.. Immature fruit, poor color Test#. Tomatoes packed commercially; VR field fruit not in commercial box Tomato quality Variety and maturity at harvest Minimize physical injury Storage: temperature & duration. C ( F), No lower than C ( F) - weeks Ripening conditions Temperature - C High humidity If MG fruit, ppm ethylene days http://www.unitedfresh.org/newsviews/food_safety_resource_center/fresh_tomato_supply_chain
Quality Criteria for Marketing Chiles and Peppers Shape, size and color typical of cultivar Bright glossy appearance; Green stem & calyx No decay, damage, defects Firm, little water loss Flavor and pungency typical of cultivar color value cm or g A Chroma Hue Volume (cm) Fresh weight (g) C mg. kg -. -h - or ng. kg -. h - x - mm, N or B Pericarp thickness (mm) Pericarp firmness (N) Soluble solids Respiration Ethylene production Bell Pepper (cv. Domino) Growth & Ripening Weeks from anthesis Weeks from anthesis Tadesse et al.,. Scientia Hort :. Bell peppers generally do not respond to ethylene Temperature has the greatest effect on color change or ripening. Holding at - C (- F) maximizes rate of color change Color changes During ripening Of peppers Fruit surface with color, Mature green in Air Mature green in Ethylene Breaker in Air Breaker in Ethylene cv. Orobelle at C ( F) color Color change of breaker stage fruit Test. C F C F C F C F C F cv Yolo Wonder To maximize quality and shelf-life of colored peppers, harvest at no more than - color; color change continues after harvest even under typical storage temperatures. Storage Conditions for Peppers High RH reduces water loss but may increase superficial decay on stems Avoid condensation, will favor bacterial decay on damaged areas Temperature: - C (- F);. C ( F) is best Shelf-life: - weeks CA not provide much benefit; low O retards color change
Chilling Injury Symptoms on Peppers and Chiles Green Breaker Ripe Ripe peppers are more chilling tolerant than green peppers Lim et al.,. HortScience :; d C (A) +d C (B) A. Visual Quality =excellent, =fair, =poor.. C F C F. C F C F. C F B. Weight Loss LSD. Jalapeño Peppers stored at temperatures for up to weeks (evaluated without transfer) Percent weight loss.... LSD. No significant changes in capsaicin content of Jalapeño peppers with time or storage temperature--in chiles of marketable quality Total capsaicinoids (mg/g DW). C. Capsaicin Content Similar results with Habanero and Serrano chiles no significant Changes in capsaicin content productions systems, Mexico Photos Jose Aguiar, UCR Field Pack Operations Field Harvest: defect sorting Plastic totes into refrigerated trailer for transport to packing house
Weight sizer GREENHOUSE PEPPERS Peppers transferred to shallow trailer Gentle dry dump Singulation for weight sizer Water spray to remove dust (chlorinated) Sponge rollers to remove excess water Weight loss in bell pepper fruits during periods of direct sun exposure, with storage for days at. C and finally total weight loss after additional days at C to simulate marketing. SUN d.c d C Volume sizer Weight Loss Hand packing Minutes at Sun Exposition. h. h. h sun Weight loss, Appearance and Firmness d Storage d. C Shelf d. C + d C hour exposure to direct sun reduces marketable quality Pepper Shrivel Rating Scale Weight loss = = - = - = - = - =excellent, =unuseable LSD.=. A. Visual Quality.......... Weight Loss Delays to cool should be less than: hours at - C (- F) hours at C ( F). Importance of water loss < no visual effect, texture - visual quality affected > shrivel, lose salability Water loss is cumulative Repacking Peppers at Distribution Center, Salable Weight Fresh Appearance Texture