Modified soluble dietary fiber from black bean coats with its rheological and bile acid binding properties

Alkaline hydrogen peroxide (AHP) was investigated to enhance the content and functionality of soluble dietary fiber (SDF) extracted from black bean coats. Compared with the content of SDF of original black bean coats 7.8%, the content of SDF of modified black bean coats was 16.9% after treated by 15% H2O2 (v/v) at pH 11 and 1:18 (w/v) as liquid-to-solid ratio for 0.5 h. Monosaccharide composition confirmed that the ratio of galacturonic acid in modified SDF (M-SDF) was higher than that of original SDF (O-SDF), and M-SDF was also with smaller molecular weight (Mw) of 1.24 x 10(6) Da and lower zeta-potential of -42.3 mV. Other structural characters were determined by FT-IR and TEM. In the range of 2-6% (w/v), both O-SDF and M-SDF showed a shear thinning behavior. The latter showed stronger gelation ability at the presence of Ca2+ evaluated by dynamic oscillatory rheometry. Moreover, M-SDF exhibited good abilities of binding bile acids in vitro. It could be concluded that M-SDF had a great potential to be applied as a novel kind of functional ingredient or additive in food industry. (C) 2016 Elsevier Ltd. All rights reserved.