Functional Components in Citrus: Alteration by Mineral Elements

Grapefruit (Citrus paradisi Macf.) contain various functional components including flavonones (naringin, narirutin), carotenoids, limonoids (limonin, nomilin, limonoid glucosides), folic acid, aurapatene, and vitamin C. The bitter compounds in grapefruit are naringin (7-β-neohesperidoside of naringenin), limonin, and nomilin. However, narirutin (naringenin 7-β-rutinoside) and limonoid glucosides are tasteless (Fong et al., 1990). Certain functional components may not be considered essential by conventional measures, but are increasingly recognized for their beneficial effects on health promotion and disease prevention. Market research data from many sources showed that consumers in the U.S., Japan, and Western Europe have already accepted the concept of biogenic diets containing biologically active functional components and are willing to try diets to prevent chronic diseases (Shukla, 1992). In recent years, many epidemiological and case control studies have shown that citrus flavonoids have potential biological activities which include antioxidant, anticancer, antiviral, anti-inflammatory activities, effects on capillarity, cholesterol lowering ability, and an ability to inhibit human platelet aggregation (Benavente-Garcia et al., 1997; Guthrie et al., 2000; Middleton and Kandaswami, 1994). Bronner and Beecher (1995) reported that average intake of flavonones from citrus juices by Americans is estimated to be about 23 mg per day while the average daily intake of flavonoids is 1 g per day (Kuhnau, 1976). The limonoids exist in citrus fruit primarily in the form of glucosides and are not bitter (Fong et al., 1990). Recent studies have shown that limonoids and their corresponding glucosides are inhibitors of chemical carcinogenesis in laboratory animals (Lam et al., 1994; Miller, et al., 1989, 2000) and in human breast cancer cells (Guthrie et al., 2000; Tian et al., 2001) as well as reduce cholesterol (Kurowska et al., 2000). Vitamin C is an essential nutrient for humans and citrus fruit as well as their processed products are the most commonly consumed sources (Kefford, 1973). Investigators have postulated a role of vitamin C in the prevention of cancer, heart disease, and in the augmentation of immune function such as in the prevention of common cold (Hemila, 1992). It is clearly established that the pigment lycopene is most Abstract