Enzymatic modification of potato starch by amylosucrase according to reaction temperature: Effect of branch-chain length on structural, physicochemical, and digestive properties

Branch-chain elongated starches can be synthesized by amylosucrase (AS). In this study, potato starches with different branch-chain length were produced using the temperature-dependent elongation property of AS from Deinococcus geothermalis (DGAS). Decreasing the reaction temperature led to a significant rise in the length of the branch-chains, in addition to amylose content. As branch-chain length increased, B-type crystal structure increased significantly alongside it, and the thermal transitions were enhanced, suggesting that the crystalline structure was further stabilized. In addition, a decrease in solubility and swelling power was observed, whereas the gelatinization temperatures and peak viscosities increased accordingly. With respect to digestive properties, a remarkable rise in slowly digestible starch (0-19.8%) and resistant starch (38.2%-62.2%) contents was observed, along with an enhanced resistance to mammalian mucosal alpha-glucosidase. In conclusion, enzymatic modification by DGAS might be an innovative method to regulate the physicochemical and digestive properties of starches.