Analysis of the Physicochemical and Structural Properties of Chestnut Starch After Thermal Processing

Chestnut is one of China's traditional export commodities in the international market and enjoys a positive reputation. Its key quality attributes are closely linked to changes in the physicochemical properties of chestnut starch after thermal processing. This study investigated the effects of different temperatures (100 °C, 160 °C, and 200 °C) and times (10, 20, and 30 min) of dry heat treatment (DHT) on the physicochemical and structural properties, as well as the functional properties of chestnut starch. The results demonstrated that DHT increased the solubility (S) and water absorption capacity (WAC), but reduced the swelling power (SP), transmittance, and gelatinization characteristics. DHT modified the starch's functional properties, increasing its digestibility. This was reflected in the rise in rapidly digestible starch (RDS) and the decline in resistant starch (RS) content. Scanning electron microscopy (SEM) revealed that cracks, crevices, and pores appeared on the starch granule surfaces after DHT. X-ray diffraction (XRD) analyses revealed that the relative crystallinity (RC) of starch decreased with higher temperatures and longer treatment times. The ability of DHT to alter the physicochemical and functional properties of starch provides foundational data for the possible modification of chestnut starch and its application in starch-based food products.