Functional properties of domestic grown colored rice treated by germination and cooking

• Main Authors: Yi-Wei Liao, 廖易煒
• Other Authors: 賴喜美
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/13260225689986451180

碩士 === 國立臺灣大學 === 農業化學研究所 === 103 === The amount of bioactive compounds in rice may be lost during processing. The objective of this study is to investigate the changes of contents of bioactive compounds (including total soluble phenolics, anthocyanins, total soluble proanthocyanins, γ-amino butyric acid, slowly digestible starch, and resistant starch) in colored rice via germination and cooking, and try to enhance and maintain the amounts of these compounds after processing. Three major parts, including germination, cooking, and debranching, are included. The soaking process required for rice germination would cause the loss of water soluble phytochemicals in brown rice. The contents of total soluble phenolics slightly increased and GABA significantly increased while the anthocyanins and proanthocyanins gradually decreased during germination. The husk of paddy could effectively prevent the loss of water soluble compounds, but it retarded the water absorption, resulting in the low degree of germination and low GABA content of germinated rough rice. In the second part, the effects of both moist-heating and dry-heating treatments were conducted. Moist-heating caused various degradations of phytochemicals. The thermal stability of bioactive compounds from high to low were GABA, total soluble phenolics, total soluble proanthocyanins, and anthocyanins. The total soluble phenolics content of red rice remained constant after dry-heating, while the total amount of soluble proanthocyanins was increased by 2-3 times. However, GABA content of all rice cultivars significantly decreased by dry-heating. Black rice was suggested to be moist-heated for keeping higher amounts of phenolics and GABA. Moist-heating treatment was suitable for retaining GABA in red rice as well. But, the dry-heating treatment was chosen for obtaining higher amount of phenolics. Slowly digestible starch (SDS) content of moist-heated and dry-heated waxy rice were 0-2.91% and 3.49-11.78%, respectively, while no resistant starch (RS) could be detected after both thermal treatments. Debranching treatment of waxy rice flour suspension with debranching enzyme, pullulanase, followed by centrifugation, condensation, retrogradation, and freeze-dried could obtain 38-42% SDS and RS contents in total. The RS content gradually increased with the increasing time period of retrogradation. Hence, enzymatic debranching treatment followed by the retrogadation treatment could be a way to produce SDS and RS in rice.