POSTHARVEST HEAT CONDITIONING EFFECTS ON EARLY-RIPENING GIALLA CACTUSPEAR FRUIT

The influence of postharvest heat conditioning at 38 degrees 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 degrees C and 90%-95% relative humidity (RH) f ollowed by 7 days at 20 degrees 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. Treatm ent for 24 to 72 h was also effective in reducing decay, with conditio ning for 23 h being the most effective. Overall visual quality was bet ter in heat-conditioned compared with control fruit. Mass loss was sig nificantly reduced by all heat conditioning treatments. Respiration ra te 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 co nditioning on juice pH, titratable acidity, soluble solids concentrati on and ascorbic acid was negligible. Prestorage heat treatment provide s some measure of CI and decay control without detrimental effects to visual quality of early ripening cactus pear fruit and may offer an al ternative to fungicide treatments.