Effects of Temperature and Ethylene on Papaya (Carica Papaya L.. Cv Sunset) Ripening

Abstract

Temperatures at or higher than 30°C adversely affected the marketability of papayas. Papayas stored at 32.5°C for 10 days failed to ripen normally as evidenced by poor color development, abnormal softening, surface pitting, off-flavor, and a higher susceptibility to decay. The rates of fruit ripening were slow at 17.5° and 20°C. Thus, the optimal temperature range from 22.5° to 27.5°C was used to establish the time-temperature relationship for papaya ripening. Skin yellowing and softening of papayas exhibited a quadratic response to ripening time within the optimal ripening range. Flesh color development of non-cold-stored fruit did not change significantly during the first six days, then rapidly increased; while that of cold-stored fruit exhibited a quadratic response for each ripening temperature. Ethylene hastened papaya ripening rate uniformly during ripening with or without cold storage. However, ethylene could not ripen immature papaya completely in terms of skin and flesh color development. Papayas treated with ethylene for 30 and 48 hrs did not show significant difference in fruit quality about one day after ethylene treatment (90 to 130 ppm). Cold-stored papayas exhibited faster ripening rate, e.g. de-greening, softening and flesh color development. Cold storage also reduced the severity of retardation on papaya ripening caused by high temperature, 32.5°C.