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Irradiation of fruit and vegetables can potentially be used by industry as a quarantine method to contain insect pests, microorganisms, and to extend shelf life. Gamma, electron beam, and ultraviolet radiation are the most frequently used radiation techniques. These radiation treatments have an effect on bioactive compounds. Grapefruit juice contains bioactive compounds such as limonoids, flavonoids, and furocoumarins. Bioactive furocoumarins in grapefruit juice have been found to increase the bioavailability of many drugs. Bergamottin, dihydroxybergamottin, and paradisin A are major furocoumarins that are shown to inhibit the activity of CYP P450 3A4 and P-gylcoprotein, which are involved in the first pass metabolism of drugs in the gut. This results in a dose-dependent increase of the drug beyond what is intended. Furocoumarins are photoreactive compounds and will readily react to ultraviolet radiation. The effect of various doses of ultraviolet radiation was investigated on `Rio Red' and `Marsh White' grapefruit. Grapefruit juice (50 mL) was irradiated with Ultraviolet A, B, and C radiation for either 5 or 10 min. Treated and control juice was extracted with 100, 50, and 50 mL of ethyl acetate. The extract was then dried and reconstituted with methanol and filtered through a 0.4-μm PTFE membrane filter. The methanol extracts were analyzed by HPLC and the concentrations of bergamottin, dihydroxybergamottin, and paradisin A were compared for UVA, UVB, UVC, and control. This project is based upon work supported by the USDA-CSREES under Agreement USDA IFAFS # 2001 52102 02294 and USDA # 2005-34402-14401 “Designing Foods for Health” through the Vegetable & Fruit Improvement Center.

Food and drug interaction has been under discussionm and specifically grapefruit and drug interaction has been under investigation, in recent years. Irradiation of food has multiple benefits in food preservation through several processes, such as sprout inhibition, disinfection, decontamination, delayed maturation, and sterilization. When ionizing radiation is passed through food, it may affect the functional components, including organoleptic characteristics. In addition to naringin, dihydroxybergamottin, paradisin A, and bergamottin, as well as their isomers, are considered putative bioactive furocoumarins present in the grapefruit juice, which interfere with the first pass metabolism of the drugs. These compounds inhibit the activity of CYP P450 3A4 and P-glycoprotein, which, in turn, will increase bioavailability of certain medications. In order to investigate the effect of pre-and postharvest practices on furocoumarins, `Rio Red' and `Marsh White' grapefruits were irradiated with 1, 5, and 10 kGys of e-beam. The irradiated fruit juice was analyzed for qualitative and quantitative changes in furocoumarins. Fifty milliliters of grapefruit juice was extracted with ethyl acetate three times and ethyl acetate extract was dried under vacuum and analyzed by HPLC. Irradiation at 1 kGys showed a decrease in the total content of dihydroxybergamottin, paradisin A, and bergamottin compared to 5 kGys, 10 kGys, and control. This project is based upon work supported by the USDA-CSREES under Agreement USDA IFAFS # 2001 52102 02294 and USDA # 2005-34402-14401 “Designing Foods for Health” through the Vegetable & Fruit Improvement Center.