Ripening Tomatoes Marita Cantwell Dept. Plant Sciences, UC Davis micantwell@ucdavis.edu Fruit Ripening and Ethylene Management Workshop Postharvest Technology Center, UC Davis, March 7-8, 0 Quality of Tomatoes Types and varieties Conventional & ESL MG & VR stages Growing areas Growing seasons All Impact Final Quality Tomato Quality Attributes Color Firmness Composition (sugars, acids, volatiles) Ripening physiology
Tomato Type & Composition, U.S. Retail Tomato Type % Soluble Solids % Titratable Acidity Grape 7. 0. Group Cherry. 0.7 Orange Cluster.70 0. Round. 0. Roma. 0. Round Cluster.0 0. Tomato Type % Soluble Solids % Titratable Acidity Cherry 7. 0.77 Campari.0 0.8 Romanita.0 0. Grape.0 0. Round greenhouse.0 0. Group Roma.0 0.7 Roma.7 0. Grape Tomato harvested at stages of maturity and evaluated at full red Initial Maturity Stage Weight per fruit, g Soluble solids, % Titratable acidity, % Red color, hue Firmness, N force.9.9 0.9.8..7.7 0.8...9 7. 0.7 7.7.7 Average 7 cvs, Cantwell, UC Davis
MG Breaker Turning Pink Light Red Red Relative Value Respiration Ethylene Red color Yellow color Aroma Flavor Sugars Soluble pectins Polymerized phenolics Green color Acidity Starch Flesh firmness Insoluble pectins Simple phenolics Time Changes during the ripening of a Climacteric Fruit Maturity & Ripening Stages MG: ethylene and temperature to ripen VR: manage ripening with temperature VR GREEN The tomato surface is completely green. The shade of green may vary from light to dark. BREAKERS There is a definite break of color from green to bruised fruit Tannish-yellow, pink or red or 0% or less of the tomato surface. TURNING Tannish-yellow, pink or red color shows on over 0% but not more than 0% of the tomato surface. PINK Pink or red color shows on over 0% but not more than 90% of the tomato surface. LIGHT RED Pinkish-red or red color shows on over 0% but red color covers not more than 90% of the tomato surface RED Red means that more than 90% of the tomato surface, in aggregate, is red *VR = vine-ripe http://www.ams.usda.gov/amsv.0/grading
Checker boarding Should never be a problem with vine ripe tomatoes! At Packhouse TOV at harvest and after days at distribution center Likely these green fruit will not ripen At Distribution Tomato mature-green and breaker stages; fruit with internal color will ripen well without ethylene treatment. For good eating quality, need at least stage MG MG MG MG MG Br
Ethylene Treatment for Ripening MG fruit Ethylene concentration: 0 00 ppm Temperature: C (0 to 77 F) Relative humidity: 90 9% Duration: to 7 hours Air circulation: sufficient for distribution of ethylene in ripening room Ventilation: sufficient to prevent accumulation of CO over % Shelf life/storage/ripening Conditions Effect of temperature on ripening rates of conventional tomato cultivars. Days to full red color at indicated temperature Ripeness stage.c F C 9F 7.C F 0C 8F.C 7F C 77F Mature-green 8 0 8 7 Breaker 0 8 Turning 0 8 Pink 0 8 For tomatoes developed with ripening mutants, fruit may require same or longer time to achieve ripening. There is considerable variation in the ripening behavior of different cultivars.
Hue 9 78 8 0 Lycopene 0..0 8..8.7 Lycopene, mg/kg FW Ripening Temp., C Red color Hue Firmness Newtons Weight loss % (7 days) 0... 9.9 9.. 9..7 8. LSD.0.8..0 0 C (8 F) C (77 F) 9 C (8 C Tomato (cv Bobcat) appearance after 7 days at indicated temperatures Initial stage
Respiration µl CO. g - h - 0 0 0 0 A. Respiration. C ( F) 0 C (8 F) 0 C (8 F) Impact of Temperature on Tomato Ripening Respiration, Ethylene and Color. Best Temperature for ripening is near 0 C (8 F) 0 7 B. Ethylene production Ethylene production nl. g - h - 0 Color Score (=green, =table-ripe) C. Color change Cv Mature-green Mountain Fresh Fruit - 0 8 0 Days from Breaker Stage Respiration (µl CO.g-h) A. Respiration 0 0 0 B. Ethylene production 0 C (8 F) C (9 F) cv Bobcat average fruits initial stage = (MG) Ripening tomatoes at C and 0 C Temperature control can effectively slow ripening of tomatoes as illustrated by the difference between & 0 C (9 & 8 F). Ethylene production (nl.g-h) Color score =green, =table-ripe 8 0 C. Red color Final 0 C C Hue (Red color). 0.8 N firmness.9 9. % soluble solids.. % acidity 0. 0.0 0 0 0 Fruit were advanced mature-green with high internal locular tissue development and were already initiating ripening) Tomatoes ripened at C may have higher gloss than those ripened at 0 C due to less weight loss C 0 C Days 7
Ripening mutants retard the ripening process Example: DFD (Delayed Fruit Deterioration) mutant Respiration, µl CO/g-h 0 8 0 8 RESPIRATION 890 X NC (Cantwell, 009) Mutant Wild Type Hybrid =mature-green, =table-ripe COLOR Mutant Wild Type Hybrid Ethylene production, nl/g-h 0 8 ETHYLENE Mutant Wild Type Hybrid 7 8 9 0 Days at 0 C 0 7 8 9 0 Days at 0 C Cantwell, UC Davis, 009 WT Mutant Hybrid 8d 8d Storage of Tomatoes. C ( F) will continue to ripen slowly No lower than 0 C (0 F) weeks Controlled atmospheres % O, <% CO Relative humidity ~8% 8
Tomatoes ripen into similar quality in temperature range from.-0 C Temp. C Initial color Days to TR Weight loss % Firmness N Red color Hue SS % Sugar mg/ml TA % Vit. C mg/00ml 0. 7.0.0.0 8. 0..8.. 8. 8..0 7.8 0.. 0..0.9.0 0.8 0. 7...0 8. 9.. 9. 0.8 9.9 0 7.. 7..0 0. 0.9.. 8.. 7.. 9.9 0.7 0. 0.0.0 9.7.9 9. 0.8 7.. 8. 0. 7...7 0. 9. Average 0C 9.0. 7.0.0 9.7 0.7.8 Average.C.9. 8.. 0.0 0.7 8. LSD.0 0..7.8 0..9 ns. Cantwell, 00 MCP#7; cv Bobcat Tomatoes were handled very carefully; therefore minimal decay Stored days Cv Bobcat Initial Color Stage =. C = F 7. C = F. C = F 0 C = 8 F It is quite common that tomatoes are held at F.. C 7. C. C Results in decay and poor color. 0 C 0 C 9
Color Changes during storage at temperatures = full red Color score C ( F) 7. C ( F) 0 C (0 F) C ( F) 9 8 7 Days Cv Bobcat, round field-grown variety 00 Ara and Cantwell Could the tomatoes reach final full red color? Subjective scoring based on USDA color scale Color Changes during storage and after transfer to 0 C at 7, and days = full red Color score C ( F) 7. C ( F) 0 C (0 F) C ( F) 9 8 7 Days Cv Bobcat 00 Ara and Cantwell 0
Objective Assessment of Color A. Red color, Hue Hue color value 0 8 Storage Temperature. C ( F) 0 C (0 F) 7.C C ( F) C ( F) LSD.0 Lower the hue value, redder the fruit Most of the fruit stored longer than week at and 7. C ( and F) had decay and did not ripen. Lycopene, mg/kg FW 0 0 0 0 B. Lycopene Storage Temperature. C ( F) 0 C (0 F) 7.C C ( F) C ( F) LSD.0 Fruit stored at C and 7. C that did not decay, lacked the ability to develop red color. 0 Weeks storage Higher the lycopene content, redder the fruit What happens when partially ripe tomatoes are stored? Greenhouse rounds Initial color = mg/g lycopene + days 0C to complete ripening = mg/g lycopene Lycopene, mg/g FW 0 0 0 C (F) 7.C (F) 0C (0F).C (F) Temperatures below the recommended reduce ability of fruit to synthesize lycopene! 0 Stored week + days 0C Stored week + days 0C Total weight loss higher with higher storage temperature ( vs %), but no important change to final fruit firmness San Martin, Hong & Cantwell UC Davis 0
cv Bobcat days at 0 C Treated h with -MCP at Breaker stage Control 00 ppb 00 ppb If cannot manage temperature, -MCP could be useful to slow ripening Control fruit. C C 0 C Tomatoes and MCP (SmartFresh ) 00ppb MCP at 0 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 Effect of -methylcyclopropene on tomato flavour components, shelf life and decay as influenced by harvest maturity and storage temperature. E. Baldwin et al., 0. J Sci Food Agric 9: 99 980.
Aroma and Sensory Harvested tomatoes green, breaker, turning and pink +/ treatment with MCP Ethylene turns on aroma synthesis in tomato Stored/ripened 8 or ºC; better aroma profile at 8 C Found no real difference between breaker, turning and pink, but aroma volatiles and sensory scores generally higher for fruit harvested with more color Minimal effect on flavor due to MCP, slightly less aroma volatile development from work of Elizabeth Baldwin, USDA, Florida SCRI workshop, Feb 0 Ripened Tomato quality Variety and maturity at harvest Minimize physical injury Storage: temperature & duration. C ( F), No lower than 0 C (0 F) weeks Ripening conditions Temperature 0 C High humidity (8%) If MG fruit, 00 ppm ethylene days Once ripening is initiated, use conditions that allow color to continue to advance keep going slowly, but not interrupt the process.