ISHS Acta Horticulturae 370: International Symposium on Tropical Fruits
EFFECT OF HOT-AIR AND HOT-WATER TREATMENTS OF PAPAYA FRUITS ON FRUITS QUALITY AND INCIDENCE OF DISEASES |
| Author: | W.T. Nishijima |
| Abstract:
Various heat treatments have been used for disinfestation of fruit flies and the control of postharvest diseases on papaya since 1939. The U.S. Department of Agriculture currently allows only papaya treated with the forced air dry heat (FADH) or vapor heat (VH) to be shipped from fruit-fly infested areas to the U.S. mainland. Both treatments take about 6 hours of gradually increasing temperatures and are completed when the fruit internal temperature reaches 47.2 C. Vapor heat differs from FADH only by the 100% relative humidity during the last phase of treatment. Neither of the treatments was designed for controlling diseases although both provide some level of disease control. Vapor heat has demonstrated to be slightly better in disease control than FADH and fruit quality are comparable. The double hot-water dip (42 C for 30 min followed by 49 C for 20 min) quarantine treatment used in Hawaii from 1984 to 1992 also controlled postharvest diseases well but fruit quality suffered because fruit were required to be harvest at a mature- green stage and the severe stress created by the treatment. Double-dipped fruits often had hard flesh, irregular ripening, scald and infection by Guignardia sp. and other fungi. The single hot-water dip (49 C for 15 min) is the optimum heat treatment for disease control of papaya diseases with minimal detrimental impact on fruit quality. The additional disease control provided by a single hot-water dip before or after FADH or VH is about the same level provided by postharvest applications of the fungicide thiabendazole applied to FADH or VH treated papaya. | |
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