Extraction optimization and constipation-relieving activity of dietary fiber from Auricularia polytricha

Auricularia polytricha-derived dietary fiber (DF) is a bio-active health-promoting compound, but limited work has been done on optimization of extraction and constipation-relieving activity. In this study, an enzymatic-chemical method to extract DF was optimized, and the results showed that optimal extraction conditions were ratio of water to A. polytricha powder 41 ml/g, 0.4% α-amylase, 1.0% protamex, and enzymolysis at 66 °C, with DF extraction rate of 56 ± 3%. Then, the constipation-relieving activity of DF was evaluated with a constipated rat model. Sprague – Dawley specific pathogen free rats were randomly divided into 6 groups, namely normal, model, Maren boluses treatment, and three DF treatment groups. Constipated rats fed with 5% A. polytricha-derived DF in place of part of the standard diet resulted in increased wet weight of feces and intestinal propulsive rate, which was associated with the functional properties of DF, including high swelling capacity, water binding capacity, fat adsorption capacity, and glucose adsorption capacity. Moreover, A. polytricha-derived DF had a positive effect on gastrointestinal hormones in rats. The results indicated that the enzymatic-chemical extraction method is effective for extracting DF from A. polytricha and the DF has high constipation-relieving activity.