IMMERSION OF CUCUMBER FRUIT IN HEATED WATER ALTERS CHILLING-INDUCED PHYSIOLOGICAL-CHANGES

Cucumber (Cucumis sativus cv. Dasher 3) fruit were immersed in water a t 25, 38, or 42 degrees C for 30 min prior to storage at 12 (nonchilli ng) or 2.5 degrees C (chilling) for two weeks to determine the effects of these treatments on chilling-induced changes in electrolyte leakag e, and CO2, and ethylene evolution. Storage at 2.5 degrees C resulted in a significant increase in electrolyte leakage, which decreased sign ificantly as immersion temperature increased. Chilled fruit had higher rates of CO2 production than did nonchilled fruit following transfer to 21 degrees C, but there was no difference due to immersion temperat ure. Following transfer to 21 degrees C, nonchilled fruit produced no detectable ethylene whereas chilled fruit produced significant amounts of ethylene. The amount of chilling-induced ethylene production decre ased with increased temperature of immersion, and this difference pers isted for at least 72 h after transfer to 21 degrees C. The amount of 1-aminocyclopropane-1-carboxylic acid (ACC) was significantly higher i n chilled than in nonchilled fruit although the amount of ACC in chill ed fruit decreased significantly as immersion temperature increased. N onchilled fruit had significantly higher ACC oxidase activity than did chilled fruit at the time of transfer to 21 degrees C, and ACC oxidas e activity decreased as immersion temperature increased.