Enzymatic synthesis of long-branched or short-branched starches with uniform molecular size

Branched starches are gaining increasing attention due to their applications in food nutrition, drug delivery systems, and material science. In this study, two types of highly branched starches with uniform molecular size (hydrodynamic radius (R_h) = 10–20 nm), characterized by long and short branches, respectively, were successfully prepared using branching enzyme (BE) and 4-α-glucanotransferase (4αGT). The findings indicate that BE preferred longer chains as substrate by showing higher activity on amylose-containing native starches and modified starches with longer chains generated by 4αGT since the longer linear chains offer more potential sites for the catalysis of α-1,6-linkage transfer by BE from Rhodothermus obamensis (RoBE). These two highly branched starches show potential as materials for developing novel small-sized starch nanoparticles for encapsulation of functional bioactive compounds and ingredients.