Bioactive micronutrients in rice varieties and their extraction efficiency

Bioactive components in rice vary according to their variety and growing condition. This study determined bioactive fat-soluble components such as carotenoids, α- & {gamma}- tocopherols (T), tocotrienols (T3) and {gamma}-oryzanols ({gamma}-O) in four varieties (white, sweet, orange and brown) of rice using a HPLC system. Rice varieties were also extracted with different compositions of water/ethanol to determine the extraction efficiency of those components. The highest amounts of carotenoids (lutein 244 μg; trans-β carotene 25 μg) and T (α-, 1.5 mg; {gamma}-, 0.5 mg) were observed in brown rice; T3 (α-, 0.07 mg; {gamma}-, 0.14 mg) in orange rice and {gamma}-O (115 mg) in sweet rice. No carotenoids were extracted using water or 40% ethanol and less than 4% of T, T3 and {gamma}-O when compared with 70% ethanol extract. The extracts were also analyzed using a high-resolution LC-MS/MS (LTQ-Orbitrap XL) method to identify the [M-H]- ions of {gamma}-O, ranging from m/z 573.3949 to 617.4211. Ten triterpene alcohols or sterol ferulates were identified in sweet rice while white, orange and brown presented 3, 8 and 8 {gamma}-O, respectively. Rice varieties rich in bioactive components can be useful for a dietary strategy for obtaining optimal health. [Supported in part by the USDA 58-1950-7-707, USA, RDA (PJ008755 ), Korea, and CAPES BEX 5547/11-3, Brazil]