Postharvest Heat Conditioning Effects on Early Ripening `Gialla' Cactus Pear Fruit

Abstract

The influence of postharvest heat conditioning at 38 °C for 24, 48, or 72 hours on ripe `Gialla' cactus pear [Opuntia ficus-indica (L.) Miller] fruit produced by the spring flush was investigated during 21 days of storage at 6 °C and 90%-95% relative humidity (RH) followed by 7 days at 20 °C and 70%-75% RH (simulated marketing). Conditioning for 24 to 72 h reduced by 50% the severity of chilling injury (CI) on cactus pears following exposure to cold storage. Treatment for 24 to 72 h was also effective in reducing decay, with conditioning for 24 h being the most effective. Overall visual quality was better in heat-conditioned compared with control fruit. Mass loss was significantly reduced by all heat conditioning treatments. Respiration rate was not affected by heat treatment. Ethylene evolution was lower in fruit heat-conditioned for 48 or 72 h than for 0 h. Conditioning for 72 h resulted in the highest fruit ethanol levels. The influence of conditioning on juice pH, titratable acidity, soluble solids concentration and ascorbic acid was negligible. Prestorage heat treatment provides some measure of CI and decay control without detrimental effects to visual quality of early ripening cactus pear fruit and may offer an alternative to fungicide treatments.