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Chemical Constituents, Dietary Fiber, and γ-Oryzanol in Six Commercial Varieties of Brown Rice from Taiwan

¹Associate Professor, Institute of Food Science and Technology, National Taiwan University. ²Graduate student and assistant professor, respectively, Department of Applied Science of Living, Chinese Culture University. ³Corresponding author. 55, Hwa-Kang Road, Yang-Ming-Shan, Taipei, Taiwan 11114, Republic of China. Phone: 886-2-28610511, ext. 31533. Fax: 886-2-28764721. E-mail: whz@faculty.pccu.edu.tw

In the interest of promoting the consumption of whole grains, the chemical constituents (moisture, protein, ash, and fat) and biofunctional components (dietary fiber and γ-oryzanol) were determined in six varieties of brown rice (five japonica and one indica) that are preferred in the form of polished rice by consumers in Taiwan. The results showed significant differences (P < 0.05) in the chemical compositions of the samples for all the measured parameters. The Koshihikari variety had the highest contents of protein and crude ash. Crop year showed significant effects on the moisture content and partly on the protein, ash, and fat contents. The total dietary fiber content of the tested rice ranged between 5.1 and 10.0%, with Kaohsiung 145 having the highest content (P < 0.05). In all varieties, the content of insoluble dietary fiber was greater than that of soluble dietary fiber. The content (mg/100 g) of γ-oryzanol ranged from 17.9 to 29.2 for the 2009 crop and from 24.5 to 41.3 for the 2010 crop. It showed that γ-oryzanol was affected by crop year and variety. The japonica types had significantly higher γ-oryzanol content (P < 0.05) than the indica type. Taikeng 9 and Tainan 11 had greater γ-oryzanol content than the other rice varieties.