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Chien Yi Wang and J. George Buta

Freshly harvested unwaxed `Marsh Ruby' grapefruit (Citrus paradisi Macfad.) were obtained from Wabasso, Fla. The fruit were treated with methyl jasmonate by dipping, pressure infiltration (82.7 kPa for 3 minutes), or vapor fumigation. Control fruit were similarly treated with distilled water. All fruit were then stored at 1°C. Samples from all treatments were transferred to 20°C for 3 days after 4 and 10 weeks of storage at 1°C for evaluation of chilling injury. Symptoms of chilling injury were negligible in all treatments after 4 weeks of storage. However, after 10 weeks of storage, moderate to severe pitting occurred in the control fruit but the severity of chilling injury was significantly reduced by methyl jasmonate treatments. The most effective treatments were either pressure infiltration using a 0.1 mm emulsion or fumigation with vapor at saturation.

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J. George Buta and Chien Y. Wang

Fourier transform infrared (FTIR) spectroscopy detected early large increases in fluid leakage from zucchini squash (Cucurbita pepo L.) subjected to a chilling temperature (5C). The increase in fluid leakage (principally water) was found after 1 day at 5C, while surface pitting was detected only after 3 days of storage at 5C. Prestorage temperature conditioning at 15C for 2 days greatly diminished the fluid leakage measured by FTIR spectroscopy after 1 day of storage at 5C. Measuring fluid leakage using FTIR spectroscopy seems to be a promising technique to detect the early onset of chilling injury.

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J. George Buta and Judith A. Abbott

Treatments to inhibit browning and maintain quality of fresh-cut `Anjou', `Bartlett', and `Bosc' pears (Pyrus communis L.) were developed. Slices of `Anjou', `Bartlett', and `Bosc' pears (firmness 22, 36, and 22 N, respectively) were dipped in solutions of 4-hexylresorcinol, isoascorbic acid, N-acetylcysteine, and potassium sorbate prior to storage in air for up to 14 days at 5 °C. Inhibition of browning without loss of firmness and with no microbial growth was achieved for the three cultivars for 14 d. Inhibition of browning during 14 d storage at 5 °C was not affected by initial firmness (21-52 N) of `Anjou' pear slices.

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Robert A. Saftner, J. George Buta, William S. Conway and Carl E. Sams

The effects of organosilicone and more conventional hydrocarbon surfactants on postharvest radiolabeled calcium (Ca) and on Ca solution infiltration into `Golden Delicious' apples were examined to provide a direct and more efficient pressure infiltration technique to increase fruit Ca concentration. Both radiolabeled Ca infiltration and the proportional increase in fruit Ca estimated by fruit weight gain from Ca solutions of known concentration were significantly enhanced by a range of surfactants having differing chemical structures. Two organosilicone surfactants, Silwet L-77 and Silwet L-7604, known for their greater capacity to lower the surface tension of solutions than conventional hydrocarbon surfactants, were the best among the surfactants tested at augmenting Ca infiltration. Applications of surfactants to fruit were as effective or more effective when used as a pretreatment rather than by mixing with Ca solutions. The applied atmospheric pressure necessary to infiltrate Ca to levels considered sufficient to maintain fruit firmness and resist decay during storage could be lowered in fruit treated with organosilicone surfactants. Postharvest surfactant and Ca treatments may offer a practical means of increasing the Ca concentration of apple fruit.

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Robert A. Saftner, J. George Buta, William S. Conway and Carl E. Sams

The effects of 36 organosilicone and conventional carbon-based surfactants on postharvest infiltration of radiolabeled and unlabeled Ca solutions into `Golden Delicious' apples (Malus domestica Borkh) were examined to devise a more efficient pressure infiltration technique to increase fruit Ca concentration. Radiolabeled Ca infiltration and the proportional increase in fruit Ca estimated by fruit weight gain from Ca solutions of known concentration were significantly enhanced by a range of surfactants having different chemical structures. Tween 60 and 80; Triton X-45, X-100, X-114, X-305, and X-405; and Silwet L-77 and L-7604 enhanced Ca infiltration. The two organosilicone surfactants, Silwet L-77 and Silwet L-7604, known for their greater capacity to lower the surface tension of solutions than conventional carbon-based surfactants, were the most effective at augmenting Ca infiltration. Applications of surfactants to fruit were as or more effective when used as a pretreatment rather than mixing the surfactant with the Ca solutions. The pressure necessary to increase Ca to levels considered sufficient to maintain fruit firmness and resist decay during storage could be lowered in fruit treated with organosilicone surfactants. Sequential postharvest surfactant and Ca treatments may be a practical means of increasing the Ca concentration in apples.

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Stéphane Roy, William S. Conway, J. George Buta, Alley E. Watada, Carl E. Sams and William P. Wergin

`Golden Delicious' apples (Malus domestica Borkh) were dipped in either distilled water, methylene chloride, or one of the following surfactants: Brij 30, Tween 20, Tween 80, Tergitol 15-S-9, and Triton X-100. The fruit then were pressure-infiltrated with a 2% solution of CaCl2. Following 4 months storage at 0 °C, fruit were removed and flesh Ca concentration analyzed. The fruit surface was observed using low-temperature scanning electron microscopy, and fruit were rated for surface injury. Brij 30 altered the epicuticular wax the least and resulted in the smallest increase in flesh Ca concentration and the softest fruit. Triton X-100 altered the epicuticular wax the most and resulted in the highest fruit flesh Ca concentration and firmest of the surfactant-pretreated fruit. Methylene chloride removed some of the epicuticular wax, and fruit pretreated with this solvent had the highest flesh Ca concentration and greatest firmness. However, all of the fruit treated with methylene chloride were severely injured.