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Maria Dolores Muy-Rangel and Marita Cantwell

Temperature management of fresh products begins with proper handling at harvest. Inadvertent abuses, such as lengthy delays to cool or exposure of harvested product to the sun, can detrimentally impact postharvest quality. We used mature-green bell peppers to determine the periods of sun exposure (midday during August in Davis, Calif.) necessary to affect quality attributes (visual appearance, gloss, weight loss, and firmness). Peppers were evaluated after cooling, storage at 7.5 °C for 3 or 7 days, and storage plus 2 days at 20 °C. The impacts of sun exposure, although sometimes barely detectable after cooling, became more noticeable once the peppers were stored. The additional transfer period to 20 °C after storage further accentuated the impact of the exposure. Depending on the experiment, sun-exposed areas reached 45 to 55 °C within 1 hour. Peppers typically lost 0.4% to 0.5% and 1.0% to 1.3% weight during 1- and 2-hour exposures, respectively. Changes in gloss and firmness (whole fruit compression and pulp penetration) were preceded by changes in visual appearance. Exposure to the sun for 0.5 hour did not impact postharvest quality of peppers. Exposures from 1 to 1.5 hours usually resulted in changes apparent only after the storage period. Such exposures are problematic in commercial situations because these peppers are unlikely to be eliminated during sorting on the packingline. Exposures of 1.5 to 2 hours usually resulted in an immediate change in appearance (pitting, blistering, color change).

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Juan Carlos Díaz-Pérez, María Dolores Muy-Rangel, and Arturo Gaytán Mascorro

Fruit water loss significantly affects the quality of bell peppers. The objective of this study was to determine the effect of fruit weight, size, and stage of ripeness on the rate of water loss and permeance to water vapor. Fruit surface area/weight ratio decreased logarithmically with increases in fruit size, with smaller fruit showing larger changes in the ratio than larger fruit. Mean water loss rate for individual fruit and permeance to water vapor declined with increases in fruit size and as fruit ripeness progressed. Fruit surface area/weight ratio and rate of water loss were both highest in immature fruit and showed no differences between mature green and red fruit. In mature fruit, permeance to water vapor for the skin and calyx were 29 μmol·m–2·s–1·kPa–1 and 398 μmol·m–2·s–1·kPa–1, respectively. About 26% of the water loss in mature fruit occurred through the calyx. There was a decline in firmness, water loss rate, and permeance to water vapor of the fruit with increasing fruit water loss during storage.

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Manuel Baez-Sañudo, Jorge Siller-Cepeda, Rosalba Contreras-Martinez, Laura Contreras-Angulo, Rosabel Velez, and Dolores Muy-Rangel

Mango `Keitt' is characterized by a poor external color development and a slightly high transpiration rate during ripening, which affect external quality. When fruit is ripening, the peel turns from a green to yellowish or dull green color, and the peel has no shine. We evaluated the effectiveness of three film coatings to reduce weight loss, improve appearance, and maintain quality during ripening of `Keitt' mango fruits. Four lots of fruits were obtained from a packinghouse in late September and transported to the laboratory. Each lot was sprayed at the commercial recommended rates with SemperFresh, Natural Shine, TFC 210, and FreshSeal coatings. Water sprayed fruits were used as a control. After applications, fruits were stored for 15 days at 22 °C and 85% RH to simulate marketing conditions. Quality parameters evaluated included weight loss (%), firmness, external and internal colors (hue, chroma, l), respiration rate (CO2 production), and chemical parameters such as pH, titratable acidity and °Brix. After 15 days, fruits coated with Natural Shine reduced 50% of the weight loss as compared to control fruits, while fruits coated with FreshSeal and SemperFresh reduced only 1.7% and 3.5%, respectively. Firmness declined from 155 N to 10 N during storage, being more evident on day 10, when fruits were table ripe. Fruits treated with SemperFresh were softer as compared with the other treatments. Titratable acidity decreased from 0.8% to 0.2% during storage and °Brix increased from 13 to 17–18 in all treatments. Fruit coated with Natural Shine had reduced weight and firmness loss. Additionally, fruits developed a better external color, with lower hue values, higher chromaticity and luminosity, which improve fruit appearance.

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Manuel Baez-Sañudo, Jorge Siller-Cepeda, Rosalba Contreras-Martinez, Laura Contreras-Angulo, Rosabel Velez, and Dolores Muy-Rangel

Bananas are usually harvested at the “all green” maturity stage in the country of origin and exported to main markets. Upon arrival, fruits are forced to ripen with ethylene and moved to market conditions to accelerate color change and ripening. Fruits exposed to low relative humidity conditions at market frequently induce browning of the peel and diminish quality. To protect fruits marketed under those conditions and to reduce peel browning, SmartFresh (1-MCP) alone or combined with two film coatings was evaluated. Banana Cavendish type fruits obtained from a warehouse at all green color stage were applied with two film coatings: 1) SemperFresh (1.2%); or 2) FreshSeal™ (3 °Brix). Additionally, a set of fruits were left as a control without coatings. Coated and control fruits were then exposed to 150 ppm of ethylene for 24 hours at 20 °C. When fruits reached color stage 3 (more green than yellow), 0 and 300 ppb of 1-MCP were applied for 12 hours at 22 °C. Fruits from all six treatments were stored at 22 °C and 30% to 40% relative humidity for 5 days to follow quality changes and browning development. Weight loss, firmness, color, pH, acidity, °Brix and appearance were evaluated daily. Control fruits, SmartFresh™ alone, FreshSeal + SmartFresh™ and both film coatings alone lost more than 10% of weight after 5 days. Only fruits treated with SemperFresh + SmartFresh™ reduced weight loss below 10%. Firmness tests indicated a higher force penetration due to dehydration of peel. Pronounced browning was observed on control fruits. SemperFresh + SmartFresh™ delayed yellow color appearance, sugar spot incidence, and peel browning development, extending shelf-life. No significant changes were observed on chemical characteristics.

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Jorge Siller-Cepeda, Manuel Baez-Sañudo, Rosalba Contreras-Martinez, Laura Contreras-Angulo, Rosabel Velez, and Dolores Muy-Rangel

Banana fruits `Cavendish' type were obtained from a warehouse at color green stage. At arrival, fruits were taken out of boxes, dipped into a thiabendazole solution for 5 minutes, dried at room temperature and separated into three lots. One lot was sprayed with Fresh Seal™ (FS) at 3 °Brix, a second lot was treated with Semper Fresh™ (SF) at 1.2%, and the third was left as a control. After that, all fruits were packed again inside the plastic bags within the original carton boxes. Film-coated and control fruits were ethylene treated for 24 hours at 150 ppm, and vented for 24 hours until they reached color 3 (more green than yellow). After that, film-coated and control fruit boxes were collected inside 238-L airtight containers to apply Smartfresh™ (SMF) treatments at 0 and 300 ppb for 12 hours at 22 °C, complementing six different treatments. Later, fruits were stored at 22 °C and 80% to 90% relative humidity for 5 days to follow up changes. Quality evaluations were registered every day, including weight loss, firmness, color, CO2, ethylene, pH, titratable acidity, °Brix, and sugar spots. SF alone and the combinations SF + SMF and FS + SMF reduced weight loss as compared with the other treatments. SMF alone or in combination with FS or SF maintained higher firmness and delayed yellow color development as compared with the other treatments. Combinations of SF or FS with SMF delayed and reduced the incidence of sugar spots as compared with control fruits. Chemical characteristics were not significantly affected by the treatments, but SF + SMF had higher acidity and a lower pH. All treatments reached between 20 and 21 °Brix after 5 days. The data show that combined treatments of SMF and film coatings reduce sugar spot incidence, improving appearance and extending yellow life of fruits.