Slow starch hydrolysis of non-glutinous rice flour and potato starch heated with taxifolin: contribution of proteins to the former and longer amylose to the latter

Abstract

Taxifolin (dihydroquercetin), which has various pharmacological functions, is contained in edible plants. Some taxifolin-containing foodstuffs such as adzuki bean and sorghum seeds are cooked by themselves and with other starch-containing ingredients. In this study, non-glutinous rice flour (joshin-ko) and potato starch were heated with taxifolin. The heating resulted in the slowdown of pancreatin-induced hydrolysis of suspendable starch in joshin-ko and soluble starch in potato starch. The products of taxifolin formed by the heating such as quercetin were combined with starch during the heating and/or retrogradation, which was converted into the suspendable starch in joshin-ko and the soluble starch in the potato. Taking the difference in protein content and amylose chain length between joshin-ko and potato starch into account, the slowdown is discussed to be due to the binding of the reaction products of taxifolin to proteins in suspendable starch in joshin-ko and to soluble amylose in potato starch.

Keywords:

• Fractionation of starch-iodine complexes
• pancreatin
• soluble starch
• suspendable starch
• formation of quercetin from taxifolin

Acknowledgement

UT thanks to Kyushu Dental University for the use of the facilities.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Japan Society for the Promotion of Science [grant number 20K05916] (2020–2022), and Wesco Scientific Promotion Foundation (2021) to SH.