Effects of Enzymolysis Coupled with Hydrothermal Treatment on Digestion and Retrogradation of Chestnut Starch

Abstract

The digestion and retrogradation performance of chestnut starch constrains the development of chestnut food industry. It is of great significance to select reasonable processing methods to regulate the digestion and retrogradation properties for the development of nutritious and healthy chestnut foods with high quality. Therefore, the effects of pullulanase enzymatic hydrolysis coupled with hydrothermal treatment on digestibility, long-term retrogradation and multi-scale structure of chestnut starch were investigated. Results showed that enzymatic hydrolysis increased amylose content, and changed chain length distribution. Short-range ordered and crystalline structures were also improved, and the starch digestibility were also reduced. Hydrothermal treatment promoted starch chain interactions, and improved short-range ordered, crystalline and nano-aggregate structures of starch, leading to the lower starch digestibility. During long-term retrogradation, due to the increase of shorter A chains and the decrease of B1 chains which are easy to rearrange, starch crystalline and nano-aggregate structures decreased, which retarded starch retrogradation. Hydrothermal treatment promoted the interactions among A chains and other molecules, and further inhibited the degree of starch molecule rearrangement, which could lead to the lower degree of retrogradation. Therefore, enzymatic hydrolysis coupled with hydrothermal treatment can be used as an effective method to regulate the digestion and retrogradation performance of starch, which could promote the development of chestnut starch-based foods with slower digestion rate and lower retrogradation degree.

Keywords

• chestnut starch
• pullulanase hydrolysis
• hydrothermal treatment
• digestibility
• retrogradation
• multi-scale structures