Effect of thermal processing on starch and micronutrients of Castanea henryi

This study investigated the effects of boiling and roasting on starch structure, digestibility, and micronutrient profiles in two cultivars of Castanea henryi. Thermal processing significantly disrupted starch crystallinity and increased pasting temperature from 68.1°C to 95 °C. Rapidly digestible starch (RDS) content increased over eightfold, while slowly digestible starch (SDS) and resistant starch (RS) declined by 64.56–84.19% and 39.00–54.36%, respectively. Vitamin E content in “Baiyan No.1” (WS) decreased by approximately 50% after thermal processing, primarily due to γ-tocopherol loss, while “Jinzhui” (YS) demonstrated greater thermal stability. Boiling reduced total carotenoid content in both cultivars, declined 26.7% in YS and 21.2% in WS, respectively. Conversely, roasting increased carotenoid content in YS by 49.68%. Thermal processing significantly altered phenolic profiles in Castanea henryi kernels, with gallic acid content increased 1.85 times in YS and 2.74 times in WS after boiling. Roasting enhanced epicatechin content by 177.0% in YS and 120.0% in WS. Antioxidant activity exhibited varietal and method-dependent responses, increasing by 155.2% in YS and 342.4% in WS. These findings provide mechanistic insights into how cultivar and thermal treatment jointly shape starch digestibility and micronutrient retention, supporting the rational design of C. henryi-based products with tailored functional and nutritional attributes.