Influence of Cooking on Anthocyanins in Black Rice (Oryza sativa L. japonica var. SBR)英文电子书.pdf

1908 J. Agric. Food Chem. 2009, 57, 1908–1914 Influence of Cooking on Anthocyanins in Black Rice (Oryza sativa L. japonica var. SBR) MIKI HIEMORI,†,‡ EUNMI KOH,† AND ALYSON E. MITCHELL*,† Department of Food Science and Technology, University of California, Davis, California 95616-8598, and Department of Nutritional Science, Faculty of Health and Welfare Science, Okayama Prefectural University, Kuboki 111, Soja 719-1197, Japan The composition and thermal stability of anthocyanins in black rice (Oryza sativa L. japonica var. SBR) produced in California were investigated. Six anthocyanin pigments were identified and quantified by high performance liquid chromatography using photo diode-array detection (HPLC-PDA) and electrospray ionization mass spectrometry [LC-(ESI)MS/MS]. The predominant anthocyanins are cyanidin-3-glucoside (572.47 µ g/g; 91.13% of total) and peonidin-3-glucoside (29.78 µ g/g; 4.74% of total). Minor constituents included three cyanidin-dihexoside isomers and one cyanidin hexoside. Thermal stability of anthocyanins was assessed in rice cooked using a rice cooker, pressure cooker, or on a gas range. All cooking methods caused significant (P 0.001) decreases in the anthocyanins identified. Pressure cooking resulted in the greatest loss of cyanidin-3-glucoside (79.8%) followed by the rice cooker (74.2%) and gas range (65.4%). Conversely, levels of protocatechuic acid increased 2.7 to 3.4 times in response to all cooking methods. These findings indicate that cooking black rice results in the thermal degradation of cyanidin-3-glucoside and concomit