Novel α-amylolyzates derived from enzymatically synthesized α-glucans using diverse glycogen branching enzymes decelerate glucose release by modulation of intestinal α-glucosidases

In this study, the internal branched structure of highly branched α-glucans (HBαGs) was regulated by employing glycogen branching enzymes (GBEs) from different microbial sources and amylosucrase, with the purpose of synthesizing structurally diverse α-amylolyzates. Variations in GBE origin resulted in HBαGs with distinct fine structural features, including differences in α-1,6 branching degree and molecular weight. Following hydrolysis with Aspergillus oryzae α-amylase, the resulting α-amylolyzates exhibited a high degree of branching (from 26.6 to 30.9%) and large molecular weight (1.07 × 10⁶ to 1.86 × 10⁷g mol^-1) after removal of linear maltooligosaccharide region. These α-amylolyzates exhibit resistance to α-amylase due to their large molecular size and dense branching structure, and therefore can be hydrolyzed into glucose only by mucosal α-glucosidase complexes, notably from rat intestinal and recombinant human sources. As a result, various tailor-made α-amylolyzate samples, specifically designed based on different HBαGs, showed a significant reduction in the glucose generation rate. This study presents various enzymatic strategies for producing structurally diverse α-amylolyzates, which are slowly degraded in digestive enzymes. These materials extend the region of glucose release and absorption within the small intestine, thereby attenuating glycemic responses and suggesting their potential as functional ingredients for regulating glucose homeostasis.