Comparative study on structure, properties, functions, and in vitro digestion characteristics of dietary fiber from Chinese chestnut prepared by different methods

This study compared the effects of enzyme extraction (E-DF), enzyme-acid extraction (EAc-DF), enzyme-alkaline extraction (EAl-DF), ultrasonic-enzyme extraction (EU-DF), and microwave-enzyme extraction (EM-DF) on the yield, chemical composition, structural characteristics, physicochemical properties, physiological activities, and hypoglycemic activities of dietary fiber (DF) from Chinese chestnut. EAl-DF had the highest yield (25.44 ± 0.70%) among all five extraction methods. The structural analysis indicated that other extracts, particularly EAl-DF, had a more complex and porous structure than E-DF. Analysis of monosaccharide composition showed that the main sugars in Chinese chestnut DF included Ara, Gal, Glc, and Man. Notably, EAl-DF exhibited the highest water and oil retention ability and hypoglycemic activity. The DFs extracted by five methods can resist digestion in the digestive tract. These results indicate that enzymatic-alkaline method is a high-quality method for extracting DF from Chinese chestnut. And this study provides a theoretical basis for the efficient preparation and development of Chinese chestnut DF.