Irradiation, stage of maturity at harvest, and storage temperature during ripening affect papaya fruit quality

Abstract

Solo-type papaya (Carica papaya L.) fruit at the mature green (MG) or one-quarter yellow (QY) stage of maturity were imported through the Port of Miami, Fla., and either irradiated (0.675 kGy) or not irradiated. Fruit condition and quality attributes were determined after ripening to the edible ripe stage at 25 °C before and after storage for 7 days at 10, 12, or 15 °C. The incidence and severity of peel scald was increased by irradiation regardless of storage and ripening regime; however, the degree of severity was dependent on fruit maturity at irradiation. Irradiated QY fruit tended to have the most serious incidence and severity of scald. Mature green fruit ripened at 25 °C without storage had the lowest incidence of fruit with hard areas in the pulp ('lumpy' fruit). The QY fruit generally were second only to irradiated MG fruit stored at 10 °C in incidence of lumpiness. Anthracnose sp. decay and stem-end-rots affected 53% of all fruit. The least decay occurred on fruit ripened at 25 °C without storage, regardless of fruit maturity, and the most decay occurred on QY fruit with or without irradiation. Fruit ripened at 25 °C without storage had more palatable pulp (5.5 N) at the edible ripe stage than did fruit held in storage and then ripened. The effect of fruit maturity or irradiation dose on fruit firmness, however, was dependent on the storage temperature. Mature green fruit ripened at 25 °C lost less weight than did those stored at cold temperatures prior to ripening. We recommend that importers obtain fruit with only a slight break in ground color, and distribute them as rapidly as possible, while maintaining transit/storage temperatures at or above 15 °C with or without exposure to irradiation.