Rheological, thermal and in vitro digestibility properties on complex of plasma modified Tartary buckwheat starches with quercetin

Starch-polyphenols complex with unique physicochemical and functional properties has gained research interests. As a method of physical modification, plasma treatment leads to smaller fragments of starch, which increases the possibility of binding with polyphenols. In this study, pregelatinized plasma-modified Tartary buckwheat starch (pre-TBS-P), as a new material, was combined with quercetin forming complexes (pre-TBS-PQ). The rheological and thermal properties, and digestibility of pre-TBS-P-Q were investigated. Results show that quercetin complexation increased the consistency coefficient and decreased the flow behavior index. A more compact and stable structure after combining quercetin was observed using SEM and TGA. The results of XRD and FT-IR identified that quercetin was bound to starch through hydrogen bonds, forming the non-inclusive complex with higher crystallinity. Compared with pregelatinized Tartary buckwheat starch (pre-TBS), the digestion rate of both pre-TBS-P and pre-TBS-P-Q decreased. The velocity constant in the first-order digestion ranked as pre-TBS < pre-TBS-P < pre-TBS-P-Q. Conclusively, using the combination of plasma treatment and complexation with quercetin, the digestion velocity of pre-TBS-P-Q complex decreased due to the increased viscosity of starch solution, as well as, the enhanced crystallinity and compactness of starch granules.

Automated summary

The study investigated the rheological, thermal properties, and digestibility of plasma-modified Tartary buckwheat starch complexed with quercetin. The results showed that quercetin increased the consistency coefficient and decreased the flow behavior index of the complex. SEM and TGA analysis revealed a more compact and stable structure after quercetin complexation, while XRD and FT-IR results indicated a non-inclusive complex with higher crystallinity formed through hydrogen bonding between quercetin and starch. Additionally, the digestion rate of the complex decreased compared to untreated Tartary buckwheat starch, attributed to increased viscosity, enhanced crystallinity, and compactness of starch granules.