Enzymatic amplification of α-1,6 linkages by glycosyltransferases on banana starches to enhance slow digestibility at the small intestinal α-glucosidase level

초록

Banana starch contains a higher proportion of long, linear B3-amylopectin chains compared to other botanical sources of starch, making it an effective substrate for glycosyltransferases. In this study, glycogen branching enzymes (GBEs) and 4,6-alpha-glucanotransferases (4,6-alpha GTs) were applied to amplify the alpha-1,6 branching structures in banana starch, which are digested more slowly into glucose by mammalian alpha-glucosidase. Both enzymes increased the proportion of alpha-1,6 linkages by efficiently utilizing the long B3-chains. GBEs amplified the number of alpha-1,6 branching points (7.0-15.6 %), while 4,6-alpha GTs enhanced the consecutive ratio of alpha-1,6 bonds (0.5-6.3 %) compared to untreated banana starch (3.5-3.7 %). Additionally, enzyme-treated starches exhibited decelerated glucose release when tested with rat intestinal and human recombinant alpha-glucosidase. These results suggest that enzyme-modified starches with enhanced alpha-1,6 branching have the potential to serve as functional carbohydrates for modulating postprandial glycemic responses. Furthermore, this approach offers a novel application for banana-based products, contributing to reduced agricultural waste and environmental sustain-ability in the food industry.

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