Elucidation of the mechanism of suppression of rice starch digestion by dietary polyphenols

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K00836
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Eating habits
• Research Institution: Sanyo Gakuen Junior College (2019); University of East Asia (2016-2018)
• Principal Investigator: Hirota Sachiko 山陽学園短期大学, その他部局等, 教授 (00312140)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: アズキポリフェノール / ヴィグナシアニジン / 飯澱粉の消化 / 胃腔条件

Outline of Final Research Achievements

Azuki bean flavonoids could suppress the digestion of starch by α-amylase, and the suppressive effects were in the order of taxifolin << quercetin < vignacyanidin. This result suggests that these flavonoids could suppress the digestion by binding to the hydrophobic region of rice starch. The suppression of starch digestion by quercetin and vignacanidin was reduced by treating with nitrite under gastric conditions, but the reaction product of vignacyanidin and nitrite could still contribute to the inhibition of starch digestion. Furthermore, it was shown that the starch digestion of rice cooked with adzuki bean was digested slowly. As the mechanism, binding of procyanidins in adzuki bean to rice starch during the cooking is proposed.

Free Research Field

食品科学、食物ポリフェノール

Academic Significance and Societal Importance of the Research Achievements

米澱粉と疎水的に結合して、その澱粉消化を抑えやすいアズキ種子の成分としてヴィグナシアニジンが明らかになり、また、アズキ飯の緩やかな澱粉消化には、プロシアニジンが関与していることも明らかになった。これらの抑制は、胃腔条件で亜硝酸と反応した後も維持された。この結果は、アズキ飯等の低消化性は、小腸でも保たれていることを示し、さらに、食物ポリフェノールを用いて、米澱粉の摂取に伴う血糖値増加を抑制できる米調理法の提案が可能となる。