EFFICACY OF IRRADIATION VS THERMAL METHODS AS QUARANTINE TREATMENTS FOR TROPICAL FRUITS

Ionizing radiation can be effectively applied to fruits and vegetables for several purposes. The most feasible and potentially useful applic ation is probably for disinfestation as a quarantine treatment. All st ages of a fruit fly will become sterile upon being irradiated at a min imum dose of 0.15 kGy, the dose level approved by the USDA in January 1989 for treating Hawaiian papayas as a quarantine procedure. This is also well below the dose level approved in April, 1986 by the U.S. Foo d and Drug Administration for irradiating fresh foods for disinfestati on and delaying maturation. Research on irradiation of several tropica l fruits such as papayas, mangoes, lychees showed that the chemical, s ensory and nutrient qualities of these fruits were well retained at 1. 0 kGy, and the fruits would ripen normally or slightly delayed. Since September, 1984, thermal methods used by the papaya industry after eth ylene dibromide was banned require treatment time of up to 7 hrs and h ave caused quality problems. Some of the fruits treated by the hot air or the double-dip hot water method lack flavor and had lumpy texture. The vapor heat method as now used is quite expensive. irradiation stu dies have proved the efficacy of the process to disinfest tropical fru its of fruit flies. Market test of irradiated Hawaiian papayas in 1987 showed that consumers preferred irradiated papayas over hot water tre ated papayas by 11 to 1. Thus the only hurdle to overcome in using irr adiation for tropical fruits is to convince the consumers that irradia ted fruits are wholesome and safe for human consumption, which has bee n amply proven with scientific data obtained during the past three dec ades, and further proven with the,marketing of irradiated fruits in th e U. S. A. since early 1992.