A facile method for isolating long branch-chains of amylopectin from starch by preheating and pullulanase treatment

Production of long branch-chains of amylopectin was significant to conftrol starch functionalities. Long branch-chains of amylopectin were currently synthesized through amylopectin elongation by amylosucrase, but this methodology was hardly industrialized because of the difficulty in large-scale production of amylosucrase. This study aimed to establish a facile method to fractionate long branch-chains of amylopectin from waxy maize starch following preheating (58–73 ℃), pullulanase digestion, and centrifugation. Results showed that amylopectin chain length was positively correlated with starch thermostability. Structures packed by short branch-chains of amylopectin would be gelatinized during preheating, and then removed from starch granules by pullulanase digestion and centrifugation to collect thermostable structures rich in long branch-chains of amylopectin. The preheating at higher temperatures promoted starch gelatinization and pullulanase digestion, and in turn, increased the content of long branch-chains of amylopectin of collected starch. By the preheating-pullulanase digestion-centrifugation treatment, the content of short branch-chains of amylopectin of starch significantly decreased from 24.04% to 19.69% and starch rich in long branch-chains of amylopectin was collected. Findings verified that long branch-chains of amylopectin could be isolated from starch granules following the combination treatments of preheating, pullulanase digestion, and centrifugation.