Applied Sciences (Apr 2025)
Changes in Physicochemical Properties and In Vitro Digestibility of Broken Rice Starch by Ultrasound and Quercetin Dual Treatment
Abstract
Applying physical modification methods to raise the resistant starch content is a feasible strategy for developing foods with a low glycemic index (GI) and regulating postprandial hyperglycemia. Here, broken rice starch (C) was modified via ultrasound and quercetin complexation (US-Q). The structure, physicochemical properties, and in vitro digestibility of the US-Q product were subsequently determined. Scanning electron microscopy (SEM) images showed that the modification changed the starch granules’ morphology, forming a more compact and stable structure. Fourier transform infrared (FTIR) spectroscopy images revealed the interaction between the starch and quercetin. An X-ray diffraction (XRD) analysis demonstrated that the crystallinity of the US-Q was lower than that of the C, indicating that the combined modification with ultrasound and quercetin disrupted the long-range ordered structure of the starch and facilitated the formation of a short-range ordered structure from amylose. Size exclusion chromatography (SEC) images showed that both the molecular weight (from 72,080.96 kDa to 85,141.95 kDa) and amylose content (from 15.94% to 26.76%) increased significantly, while the branching degree and average degree of polymerization of amylopectin decreased, suggesting that the ultrasonic treatment processing method had a significant impact on the formation of the quercetin–starch complexes. In terms of in vitro digestion, the resistant starch content of the US-Q was significantly increased from 6.57% to 20.23%, whereas the hydrolysis rate was decreased from 92.6% to 78.35%, indicating that the presence of quercetin reduced the digestibility of the starch complexes by inhibiting the starch-hydrolyzing enzyme activity. Overall, this study improves the understanding of ultrasound and quercetin dual treatment of broken rice starch, providing a theoretical basis for the development of low-GI starch foods for industrial applications.
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