Phytochemicals and glycemic Index analyses of domestic rice cultivars - 農業知識入口網

Abstract

Oryza sativa, Asian rice, feeds about a half population worldwide. Its seeds are a nutritious food source, especially its bran (aleurone layer). It possesses
abundant phytochemicals, such as - oryzanol, tocopherols and tocotrienols. By breeding with interspecific hybridization of varieties Indica and Japonica
were employed to obtain new cultivars; many had become representatives of  High-Quality Rice in Taiwan. The bioactive ingredients vary in content with
different degrees of milling conditions. It was conducted with a-10 second per milling for several lines or cultivars of the brown rice grain, until the brown
surface turning to white (as the commercial polished rice). Averagely, four layers of the bran portion could be collected and the contents of these bioactive 
ingredients reached a peak in the second or the third layer. Additionally, embryos of the rice grain were also analyzed, which were divided into intact and 
ground categories. Results showed that  approximately 3 to 4 folds of the concentrations of those in the ground embryos were detected compared to the
intact form. Besides, 13 cultivars of brown and white rice samples were employed  for the analysis of estimated glycemic index (EGI). Results showed that
the brown and white rice of the TCS10 rice cultivar (both belonged to the low GI level in the human study) were low and  medium GI food, respectively. All
brown rice samples of the thirteen cultivars were evaluated as low GI rating.