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of apple slices. Hexanal has also been used to control postharvest decay in stone fruit incited by Monilinia laxa and Rhizopus stolonifer ( Caccioni et al., 1995 ). Hexanal has other properties in addition to its antimicrobial activity. Aroma

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within a day or two after the fruit has been inoculated, and because the pathogen is strictly a wound invader, the harvest and subsequent packinghouse handling are particularly hazardous periods. Two other types of decay pathogens have been associated

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Giambanco de Ena (1997) and previous experiences on commercial storage of melon hybrids to induce CI without exacerbating decay ( Valdenegro et al., 2005 ). After this time, fruit were examined for CI and other disorders, decay, loss of whole fruit finger

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further characterization of this scarring has been conducted and processors are concerned that it may reduce peel integrity and/or increase fruit decay before processing. In Florida, harvested oranges for processing are transported to the processing plant

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Acetic acid (AA) as a vapor at low concentrations was effective in preventing fruit decay by postharvest fungi. Fumigation with 2.7 or 5.4 mg AA/liter in air at 2 and 20C reduced germination of Botrytis cinerea Pers. and Penicillium expansum Link conidia to zero after they had been dried on 0.5-cm square pieces of dialysis tubing. Decay of `Golden Delicious', `Red Delicious', and `Spartan' apples (Malus domestica Borkh.) inoculated with 20 μl drops of conidia of B. cinerea (1.0 × 105 conidia/ml) or P. expansum (1.0 × 106 conidia/ml) was prevented by fumigating with 2.0 and 2.7 mg AA/liter, respectively. Tomatoes (Lycopersicon esculentum Mill.), grapes (Vitis vinifera L.), and kiwifruit [Actinidia deliciosa (A. Chev.) C.F. Liang et R. Ferguson var. deliciosa] inoculated with B. cinerea or navel oranges (Citrus sinensis L.) inoculated with P. italicum Wehmer did not decay when fumigated with 2.0 mg AA/liter at 5C. AA fumigation at low temperatures (1 and 5C) with 2.0 or 4.0 mg AA/liter prevented decay of `Spartan' and `Red Delicious' apples and `Anjou' pears (Pyrus communis L.) inoculated with B. cinerea and P. expansum, respectively. `Spartan' apples immersed in a suspension of P. expansum conidia (1.4 × 105 conidia/ml) and fumigated with 2.7 mg AA/liter at 5C had an average of 0.7 lesions per fruit compared to 6.1 for nontreated fruit. Increasing the relative humidity from 17% to 98% increased the effectiveness of AA fumigation at 5 and 20C. At the concentrations used in our trials, AA had no apparent phytotoxic effects on the fruit. The potential for commercial fumigation with AA to control postharvest decay of fruit and vegetables appears promising.

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Abstract

Curing of sealed lemons of normal and decay-prone types [Citrus limon (L.) Burm.f] and of sealed Goliath pomelo [Citrus grandis (L.) Osbeck] inhibited postharvest decay without deleterious effects on fruit quality and prevented the development of Penicillium digitatum on inoculated fruit. Curing of nonsealed fruit was less effective in reducing decay than curing sealed fruit and caused prohibitive weight loss, shrinkage, and softening. Curing of sealed and waxed ‘Shamouti’ and ‘Valencia’ oranges (C. sinensis), in comparison to only sealed fruit, resulted in some CO2 injury of the peel and off-flavor.

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Previous research suggests that treatment of sliced or vacuum-infiltrated tomato fruit with calcium chloride (CaCl2) solutions may reduce decay, but no work on dipping whole tomatoes has been reported. In the present experiments, `FL 47' tomato fruit were collected at the mature green or pink stage from a local packinghouse, held at 12.5 or 25.0 °C overnight, and then dipped in solutions with 0.5% to 5% CaCl2 with or without 150 ppm sodium hypochlorite. Fruit were dipped for 1 to 4 minutes at temperatures ranging from 0 to 35 °C. Mature green fruit dipped in solutions with 0.5% and 1.0% CaCl2 at 35 °C had significantly lower rates of decay following storage at 12.5 °C (90% RH) than the control (27% vs. 36% decay, respectively). These fruit were also significantly softer after 2 weeks of storage than control fruit (0.85 mm vs. 0.74 mm deformation, respectively) and appeared to be slightly more ripe. Decay in fruit dipped in 2% CaCl2 was not significantly different from the control, while fruit dipped in 3% to 5% CaCl2 developed significantly more decay than control fruit. The CaCl2 treatments had no significant effect on decay of fruit treated at the pink stage and none of the treatments at 0 °C significantly affected postharvest decay. Dips in 2% to 5% CaCl2 significantly increased tomato peel calcium content after storage. Dipping time had no significant effect on peel calcium content.

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Effects of 10% plant oils (corn, soybean, peanut, canola, sunflower, safflower, rape seed, linseed, and cottonseed), 100 mg·L-1 chlorine, or 100 mg·L-1 chlorine plus 10% oil combinations on pathogen (B. cinerea, P. expansum, or G. cingulata) infection and fruit decay in `Delicious' apples and `Ya Li' pears were studied. None of the oils showed inhibition on spore germination of the three pathogens by in vitro test. In inoculated fruit, oil treatments did not affect incidence but reduced severity of decay after 6 months storage at 0 °C plus 7 days at 20 °C, but no difference was found among the oils at the same concentration. In non-inoculated fruit, oils reduced fruit decay to low levels (4%) even in the most severe season. Oils also maintained fruit quality attributes, reduced water loses, and controlled scald in apples and internal browning in pears. Chlorine reduced incidence but did not reduce severity in decayed fruit. Fruit first drenched with chlorine then dipped in oil emulsions without pathogen inoculation remained decay free, while control fruit developed 10% to 15% or 13% to 23% decay after 6 months at 0 °C plus 7 days at 20 °C in both apples and pears, respectively.

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Management of pear (Pyrus communis L.) trees for low N and high Ca content in the fruit reduced the severity of postharvest fungal decay. Application of N fertilizer 3 weeks before harvest supplied N for tree reserves and for flowers the following spring without increasing fruit N. Calcium chloride sprays during the growing season increased fruit Ca content. Nitrogen and Ca management appear to be additive factors in decay reduction. Fruit density and position in the tree canopy influenced their response to N fertilization. Nitrogen: Ca ratios were lower in fruit from the east quadrant and bottom third of trees and from the distal portion of branches. High fruit density was associated with low N: Ca ratios. Nutritional manipulations appear to be compatible with other methods of postharvest decay control.

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Phomopsis cucurbitae is a latent infecting pathogen that infects unripe muskmelon fruit, but causes decay after harvest. This fungus causes severe losses during muskmelon fruit storage and marketing in the U.S., Japan, and some Central American countries. Previous studies showed that the fungus produced the cell wall-degrading enzyme polygalacturonase (PG) in both culture and muskmelon fruit tissue. The role of P. cucurbitae PG in the fruit decay process and its relation to latent infection is not well-understood. A prominent PG isozyme produced by the fungus in decayed fruit was purified to homogeneity by a sequence of extraction, ultrafiltration, preparative isoelectric focusing, anion exchange, and gel filtration chromatography. This isozyme exhibited endo-activity, a molecular weight of 54 kDa according to SDS-PAGE, and a pI of 4.2 based on IEF-PAGE. Isozyme activity was optimal at 40–45°C and pH 5.0. It had a Km of 44.7 g/ml and a Vmax of 0.313. The purified isozyme also effectively macerated mature muskmelon fruit tissues. This isozyme was the most prominent of the PG isozymes produced by P. cucurbitae in decaying fruit, and may play an important role in postharvest decay.

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