Introduction. Calcium chloride (CaCl2) treatment has been shown to increase the shelf-life of fruits, mainly through making cell walls less accessible to pathogens and softening enzymes. Materials and methods. bananas of four cultivars [`Ambon' (AAA), `Embul' (AAB), `Kolikuttu' (AAB) and `Seenikehel' (ABB)] were dipped in or pressure infiltrated with 4% CaCl2. To determine the effect of exogenous ethylene on treated fruits, they were ripened with exogenous ethylene. Ca2+ in cell wall fractions were monitored by atomic absorption spectrophotometry. Cup plate assays were performed to determine pectinase activity. Results and discussion. Pressure infiltration accelerated ripening and disease, and reduced firmness (P < 0.05). However, when exposed to ethylene, CaCl2 pressure-infiltrated bananas were insignificantly firmer than distilled water-infiltrated and ethylene-ripened bananas, showing a significant interaction (P < 0.05) between infiltration treatments and ethylene ripening. There was no consistent increase in covalently bound pectin of cell walls as seen in fruits that respond positively to CaCl2. Firmness reduction and ripening acceleration by Ca2+ treatment cannot be explained if polygalacturonase (PG) (known to be inhibited by Ca2+) was the dominant pectinase. Enzyme assays gave evidence of PG activity. When ammonium oxalate (known to bind Ca2+) was eliminated from the test medium, pectinase activity increased with increasing pH (pH 5 to 9). The presence of a pectinase enzyme which exhibits activity in the presence of Ca2+ is apparent. Conclusion. Ca2+ does not appear to influence cell wall structure of bananas but appears to influence ripening physiology.

Introduction. Apples are potentially subject to blue mold decay caused by Penicillium expansum ifstored at 1 °C for three or more months or if wounded during handling. Results from trials with applescontaminated with conidia of P. expansum and fumigated in small chambers with acetic acid (AA) vapor indicatedthat fruit could be sterilized to reduce decay without effect on fruit quality. The objective of this study was todetermine if larger quantities of apples treated with AA vapor would have less decay after storage and/or wounding. Itwas also important to determine if fumigation would affect apple quality and aroma. Materials and methods. Applecultivars were harvested at commercial maturity for use in AA fumigation trials. Apples artificially or naturallycontaminated with conidia of P. expansum were fumigated with AA vapor in a 1 m3 gas tight chamber at10 °C for 1 h to 24 h or dipped in 450 μg thiabendazole × L-1 solution. Fruit fumigatedin standard wooden or plastic apple boxes, or small wooden bins were either wounded and evaluated for decay after a weekat 20 °C or stored at 1 °C for three or more months and evaluated for decay. Then apple quality wasassessed. Results. Apples naturally contaminated with Penicillium spp. that had been stored at1 °C in air storage and treated with AA vapour had 50% less decay than the control fruit. In anotherexperiment, AA fumigation was as effective as thiabendazole in reducing decay. AA fumigation reduced decay of fruitcoming out of storage for apples stored for 3 months, and a second AA fumigation reduced infection of wounds on thesesame apples. AA fumigation before storage did not affect apple quality or vinegar aroma. Discussion. AA fumigationshowed great potential for reducing decay in stored apples. It could be used as an organic alternative to syntheticfungicides for control of blue mold decay.

Introduction. Sweet cherries are susceptible to postharvest decay. The use of synthetic fungicides is discouraged in postharvest handling because they can leave a residue and present a safety risk. Therefore, naturally occurring compounds have been considered as an alternative. Fumigation of short-chain organic acids and essential oils has shown promise in controlling fungal activities. This study reports their effects on sweet cherries. Materials and method. `Hedelfingen' sweet cherries (Prunus avium L.) were inoculated with conidia of Monilinia fructicola and Penicillium expansum, then fumigated with three levels of thymol or acetic acid for 10 min before cold storage. Results and discussion. After 13 d at 10°C, sweet cherries fumigated with 10 mg × L-1 of thymol significantly reduced brown rot from 21% to 12%, but had no effect on reducing blue mold rot. Fumigation with 6 or 10 mg × L-1 acetic acid significantly reduced blue mold rot from 16% to 2%, but had no effect on reducing brown rot. Fumigation did not have any effect on the firmness, total soluble solids and titratable acid of the sweet cherries. Fumigation with 2 or 6 mg × L-1 of thymol did not accelerate stem browning compared with the control, but fumigation with 10 mg Yen L-1 of thymol caused almost total stem browning. Fumigation with acetic acid showed no impact on discoloration of the stems. Conclusion. Thus, fumigation with acetic acid or thymol at low concentrations has a potential use for postharvest decay control without adverse effects on fruit quality.