Ripening pawpaw fruit exhibit respiratory and ethylene climacterics

The ripening behavior of the native American pawpaw (Asimina triloba (L.) Dunal.) fruit was studied immediately after harvest and after 1 month of 4°C storage. Fruit were harvested at two different maturity stages. Fruit that were unripe (minimal softening evident) at harvest exhibited respiratory and ethylene climacterics at 3 and 5 days postharvest, respectively, at ambient temperature, and a precipitous decline in fruit firmness was evident prior to the climacteric peaks. Fruit classified as having commenced ripening (some softening evident) at harvest exhibited both respiratory and ethylene climacteric peak at 3 days at ambient storage temperature. Fruit in cold storage at 4°C for 28 days exhibited minimal to no loss of firmness, and upon removal to ambient temperature both respiratory and ethylene climacterics occurred within 7 days for both harvest maturities. The maximum rates of respiration and ethylene production in these studies were: CO₂ production 90 mg kg^-1 h^-1 and C₂H₄ production 14.4 μg kg^-1 h^-1, respectively. These results indicate that pawpaw fruit ripening is climacteric.