Suppression of Pancreatin-Induced Digestion of Starch in Starch Granules by Starch/Fatty Acid and Starch/Flavonoid Complexes in Retrograding Rice Flour

Abstract

Adzuki beans are used to prepare foods with glutinous and non-glutinous rice in Japan, and adzuki bean pigments are able to color rice starch a purplish red. This study deals with the adzuki bean extract-dependent suppression of starch digestion of non-glutinous rice flour (joshinko in Japanese), which was gelatinized in boiling water and then cooled to 37 °C. Accompanying the treatment of joshinko with pancreatin, amylose and amylopectin were released from the joshinko particles, and the released amylose and amylopectin were further digested. The adzuki extract suppressed the release and digestion by binding to amylose and amylopectin, which were present in the particles and at the surfaces of the particles. Fatty acids and flavonoids in the adzuki extract contributed to the suppression. In addition, the starch digestion in the joshinko particles appeared to be suppressed if the amylose/fatty acid complexes and amylose/flavonoid and amylopectin/flavonoid complexes, which are poor substrates of α-amylase, surrounded the particles. It is discussed that the suppression was due to the prevention of α-amylase access to the particles.

Individual or mixing extrusion of Tartary buckwheat and adzuki bean: Effect on quality properties and starch digestibility of instant powder

“…On the other hand, it has been reported that extrusion caused the formation of amylose-lipid complex and its supramolecular structure and then retained the crystallinity structure, which decreased the degree of gelatinization ( 15 , 34 ). Moreover, in contrast to ME, the instant powder obtained with IE possessed a higher flavonoids content ( Table 2 ) that can more effectively prevent the development of starch-iodine complex, decreasing the DG value ( 35 ). Therefore, the difference of DG between IE80 and ME80 could be influenced by these two factors.…”

Adzuki bean (Vigna angularis): Chemical compositions, physicochemical properties, health benefits, and food applications

“…Traditionally, adzuki beans are cooked with rice in the East Asia region. The flavonoids from the adzuki bean, such as quercetin and vignacyanidin, could interact with rice starch to form hydrophobic starch/flavonoid complexes, resulting in the suppression of pancreatin‐induced digestion (Hirota & Takahama, 2018). In addition, the colored rice was digested more slowly in vitro than the normal rice, probably owing to the covalent bond between rice and procyanidins and their oxidation products formed during cooking (Takahama et al., 2019).…”