Treatment of corn bran dietary fiber with xylanase increases its ability to bind bile salts, in vitro

A corn bran fiber (CDF) was further treated by xylanase and the product – XMF was obtained. Response surface methodology (RSM) was used to optimize the hydrolysis conditions (pH, time and enzyme dosage), binding of cholate (BSC), chenodeoxycholate (BSCDC), deoxycholate (BSDC) and taurocholate (BSTC) by XMF were determined. The influence trends of 3 factors were dissimilar, pH affected the binding capacity most significantly, then hydrolysis time, lastly the dosage. The optimized conditions were pH 5.3, 1.75 h and enzyme dosage 0.70 g/100 g CDF, the values for BSC, BSCDC, BSDC and BSTC were increased to 1.88, 2.34, 1.67 and 2.08 fold of CDF, respectively, which were not significantly different from those predicted (p < 0.05). There was not correlation between the bindings of any two bile salts by XMF, which indicates that the binding mechanisms of different bile salts by XMF studied here are different. The TDF, IDF and SDF content of XMF were increased by 12%, 12% and 285%, respectively. The WHC, SW and OBC of XMF were 1.11, 1.34 and 1.87 fold of CDF, respectively.