Irradiation applications to improve functional components of fruits and vegetables
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Fruits and vegetable are part of our daily diet and it is important to understand the role of postharvest treatment effects on functional components including organoleptic characteristics. Irradiation has multiple benefits in food preservation through several processes such as disinfestations, delaying maturation, sprout inhibition, decontamination, and sterilization. Sensory evaluation studies in different commodities indicate that irradiation treatment does not affect quality and flavor. Quality retention, along with efficacy and efficiency, is critical for many postharvest treatments. Although irradiated fruit retained quality compared to control, very little information is available on the effects of irradiation on functional components. Accumulative evidences from epidemiological, case and cohort studies have shown that functional components such as flavonones, flavonols may prevent chronic diseases such as cancer and cardiovascular diseases. In this chapter, emphasis is given to onion and grapefruit to illustrate the effects of irradiation on functional components. In onion, our results have demonstrated that irradiation at 0.8 and 1.2 kGy doses significantly increased both free and total quercetin concentrations. During the last four decades, ionizing radiation has been used as a quarantine treatment for eight fruit hosts that are shipped from Hawaii to the USA mainland. Flexibility and effectiveness of irradiation as a quarantine treatment have been demonstrated and proven to be appropriate for tropical fruits crops. However, several recent studies indicated the need of irradiation as an alternative for quarantine treatment in citrus to prevent infestation of Mediterranean (Ceratitis capitata (Weid), Mexican (Anastrepha ludens (Loew), and Carribbean (A. suspensa (Loew)) fruit flies. Our studies, in citrus, showed that low doses of ionizing radiation significantly increased flavonone concentrations. Potential use of irradiation to enhance the levels of functional components is discussed. To remain competitive in international and national markets, optimization of these components may be important for the processing industry. 2004 American Chemical Society.