Physicochemical Properties and in Vitro Digestibility of Dejiang Gastrodia elata Powder with Different Particle Sizes

To explore how particle size affects the physicochemical and in vitro digestion properties of Dejiang Gastrodia elata powder, this study ultrafinely ground the material into four fractions (50, 100, 200, and 300 mesh). Their microstructure, physicochemical properties, antioxidant activity, and in vitro digestion were examined, and principal component analysis (PCA) was used to identify the optimal grind size. The results showed that the grinding treatment mainly modified the physical morphology of Dejiang G.elata powder, while its molecular structure unchanged. The angle of repose and slip angle of the powder increased with decreasing particle size, whereas the bulk density, water-holding capacity, and oil-holding capacity decreased. The 200-mesh powder exhibited significantly higher soluble sugar content (13.43%) than the other particle sizes (P<0.05). Although no significant differences in polyphenol content were observed across particle sizes (P>0.05), the 50-mesh powder showed notably higher flavonoid (4.51%) and vitamin C (4.50 mg/100 g) contents (P<0.05), and the 100-mesh powder showed notably higher antioxidant capacity (P<0.05). During in vitro simulated gastrointestinal digestion, the 200-mesh powder exhibited significantly higher soluble sugar release, whereas the 300-mesh powder showed greater polyphenol release than the other particle sizes (P<0.05). PCA identified 50-mesh as the optimal particle size for Dejiang G. elata powder. Collectively, quality differs by particle size,with 50-mesh powder showing the best overall properties, which provided a reference basis for further in-depth research on G. elata powder.