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J. H. MOY and M. E. Q. Reyes. Dept. of Molecular Biosciences & Bioengineering, Univ. of Hawaii, 1920 Edmondson Rd., Honolulu, HI 96822 The application of irradiation to fruits in recent years has provided a needed alternative in disinfestation technology and an opportunity to explore shelf life extension of some of these commodities. Radiation processing does not cause health consequences and ozone depletion as chemical fumigation does. Irradiation also allows normal ripening and retention of product quality at the required minimum quarantine dose of 0.25 kGy as compared with heat treatment. However, every fruit has its limit to the amount of radiation it can receive. Its physiological response to radiation is represented by three zones: normal tolerance, transition, and some undesirable changes. Dose rates in the radiation field of a research, pilot plant, or commercial irradiator, whether its source is gamma, electron beams, or X-rays, are never uniform. Factors contributing to dose rate variations include product density differences, distance between products and radiation source, and variation in photon or electron flux. Some commercial irradiators exhibit maximum to minimum dose rate variation by a factor of 3. The objective of our study was to determine the tolerance doses of tropical fruits when irradiated in the upper dose range (ca. 3 x 0.25 kGy). Experiments on commercial grade papaya, longan, mango, and carambola included chemical, nutrient, and physical analyses and sensory tests on fruits irradiated between 0 and 0.75 kGy at one research and one commercial irradiators. Example of results showed vitamin C contents in longans with 95.9 mg/100g by gamma irradiation, 92.8 mg/100g by X-irradiation, and 96.3 mg/100g in control fruits. Overall experimental results showed these fruits tolerate radiation dose to 0.75 kGy with normal ripening and quality retention, with only a few insignificant quality changes.The fruit industry has gained useful information that these export-grade tropical fruits have a high tolerance for irradiation, which is an efficacious quarantine treatment process.
Session 96, Fruit & Vegetable Products: General II
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |