Optimization of the Kudzu Resistant Starch Preparation Based on Debranching and Recrystallization and its Structural Properties

Kudzu-resistant starch was prepared by pullulanase debranching recrystallization. Based on single factor experiments, the response surface optimization method was used to analyze the optimal conditions for the preparation of kudzu-resistant starch. The results showed that the highest yield of 90.46% was obtained at the enzymatic reaction time of 4 h, temperature of 56°C, and amount of enzyme being 57 U/g. After debranching, the content of the resistant starch was higher than native starch. The crystal structure of the debranched starch changed from A-type to a mixture of B+V-type. The results of scanning electron microscope showed that the surface of the native starch granule was smooth and varied in size, showing a spherical or irregular polyhedral shape, while the debranched starch granule was irregular in shape and size and the surface was rough and gully. The granule morphology of the modified starch granule was also changed.