Exploring the relationship between nutritional properties and structure of chestnut resistant starch constructed by extrusion with starch-proanthocyanidins interactions

Driven by the high economic value of chestnut, creating chestnut-based food with nutritional functions has become a hot spot in food industry. In this study, effect of hot-extrusion treatment (HEX) with starchproanthocyanidins (PR) interactions (HEX-PR) on chestnut starch (CS) nutritional properties was evaluated from the perspective of structural changes. Results showed that HEX-PR promoted the formation of ordered structure of CS containing single helix, V-type crystalline structure, and starch aggregates, thus increasing the resistant starch (RS) content from 3.25 % to 12.35 %. For the nutritional evaluation, the alpha-amylase inhibitory activity, antioxidant activity and antiglycation activity of HEX-PR treated CS (HEX-PRS) were enhanced, and the enhancing effect became stronger as PR concentration rose. In addition, HEX-PRS increased the level of short chain fatty acids (SCFAs), especially propionate, and meanwhile enriched beneficial intestinal bacteria especially the Bifidobacterium. Notably, correction analysis showed that the microbial community was closely related to the alpha-amylase inhibitory activity, antioxidant activity and antiglycation activity. Overall, this study provided an approach for improving the nutritional functions of starch, and could offer guidance for further investigations to improve the nutritional quality of chestnut starch-based foods.