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 branchchains 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 & DEG;C), pullulanase digestion, and centrifugation. Results showed that amylopectin chain length was positively correlated with starch thermostability. Structures packed by short branchchains 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 preheatingpullulanase 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.