LAUSR

Objectives Epidemiological evidence suggests that common beans are hypolipidemic agents and therefore able to alleviate obesity and cardiovascular disease. The observed positive effect of bean consumption on blood lipid levels is mainly attributed to their high content of dietary fiber (DF) and it is linked to the ability of DF to interfere with lipid digestion in different ways. Some proposed mechanisms are related to the physicochemical properties of DF and involve binding of bile acids (BA) which could decrease the rate of lipid digestion and absorption in the duodenum. This study aimed to investigate the effect of bean matrices varying in structure, content and distribution of DF fractions on lipid digestion kinetics in vitro. Methods Structurally different bean matrices obtained by several processing techniques (i.e., hydrothermal, high pressure and mechanical treatments) as well isolated DF fractions were investigated. b-glucan was used as comparison. The viscosity, particle size and water and oil-binding ability of bean matrices were determined. We used dialysis, under duodenal conditions and HPLC analysis to determine BA-binding capacity. A standardized multistage static in vitro digestion protocol was used to assess the effect of bean matrices on the lipolysis rate of extrinsic lipids. Results Beans matrices reduced the extent and rate of digestion of corn oil compared to blank, with the water-soluble DF showing the largest reduction. Hydrothermal-treated beans and bean matrices with larger particle size showed the lowest capacity to retain BA and consequently were less effective at reducing the extent of lipolysis. The lower lipolysis rate observed in specific samples was related to their higher BA-binding. Conclusions Different processing variables generated bean microstructures with different potential to modulate lipid digestion. Overall, processing decreased the ability of bean matrices to delay lipolysis. Isolated bean DF has the potential to control lipolysis depending on DF distribution and BA-binding ability. However, none of the bean matrices reached the levels observed with b-glucan. Funding Sources US Dry Bean Council and Hatch Program (NIFA), USDA.