Determining the Tolerance of Plant Products inRadiation Disinfestation and Quarantine Treatment

摘要

Low dose applications of ionizing radiation to food products are showing greatcommercial promise such as disinfestation to control insect pests on foods, and quarantinetreatment (at 0.25 kGy) of plant products such as fresh fruits to be sent to distant markets.Three criteria are usually applied to judge the efficacy of the radiation process: effectiveness,efficiency, and product quality retention. The effectiveness of using radiation to control allspecies of fruit flies has been well established with ample research data, and the processefficiency is high. The third criterion on product quality requires determining the degree oftolerance a plant product exhibits in response to the radiation treatment.Tolerance dose for a plant product to be irradiated can be defined as the ‘highest’ dose a hostmaterial can receive without any noticeable or measurable external or internal adverse changesin its quality. The determination includes testing of the chemical, nutrient, physical and sensoryquality of an irradiated food against a non-treated control. The maximum/minimum dose rateratio in a particular irradiator is part of the process variables. When the ratio is high, such as 2.5to 3.0 in some irradiators, one must determine if a fruit can tolerate this dose (3 × 0.25 kGy =0.75 kGy).Results of experiments at the University of Hawaii have shown that most tropical fruits, e.g.,papaya, mango, carambola, litchi, longan, rambutan, etc. tolerate irradiation to 0.75 kGy orhigher without any adverse changes in quality. Atemoya irradiated at 0.50 kGy sometimesshowed some browning of the pulp. Avocado (cv. Shawal) does not tolerate irradiation at a lowdose of 0.25 kGy, probably because the oil in avocado is sensitive to irradiation. This studyprovided useful findings to the fruit industry that most tropical fruits have a high tolerance forradiation in the dose range needed for disinfestation and quarantine treatment.