Modification of foxtail millet (Setaria italica) bran dietary fiber by xylanase-catalyzed hydrolysis improves its cholesterol-binding capacity

In order to improve the cholesterol-binding capacity (CBC) of foxtail millet bran dietary fiber (FMBDF), xylanase-catalyzed hydrolysis was used. Single-factor experimental design and orthogonal experimental design were applied to optimize the hydrolysis conditions. The optimal hydrolysis conditions were as following: hydrolysis pH 3.8, xylanase dose 50 U/g FMBDF, hydrolysis temperature 50 °C and hydrolysis time 2 h. Under above conditions, the CBC value (11.57 mg/g) of the xylanase modified FMBDF (X-FMBDF) was 2.23 fold of FMBDF (5.19 mg/g). Analysis of monosaccharide composition, infrared spectrum and scanning electron microscopy showed that xylanase treatment could change the monosaccharide composition and microstructure of FMBDF, which contributed to the binding of dietary fiber to cholesterol. It was suggested that enzymatic treatment was a good method to modify the functional properties of dietary fibers.