Retention of primary bile salts by dry beans (Phaseolus vulgaris L.) during in vitro digestion: Role of bean components and effect of food processing

Abstract

The positive effect of common beans on reducing blood cholesterol levels has been linked to their ability to sequester bile salts (BS) and prevent their recycling. We have examined the preferences of major bean components (soluble/insoluble fiber, starch and proteins) to retain BS, and the role played by the bean matrix. Additionally, the kinetics of BS-release were evaluated in bean flours generated by a combination of hydrothermal or high-hydrostatic pressure (HHP), and mechanical treatments. An in vitro digestion model combined with dialysis was used to evaluate separately the retention of primary individual BS. Soluble fiber retained a significant proportion of BS mainly due to an increased digesta viscosity; however, the protein fraction exhibited the greatest BS retention without affecting viscosity. The thermal properties of proteins and starch were more significantly affected in presence of tauro-chenodeoxycholate, which correlated to the affinity of both fractions to retain more hydrophobic BS during digestion. Glyco-chenodeoxycholate and tauro-cholate were the most and least effectively retained BS by bean flours, respectively. Neither of the processing treatments had an impact on the binding preferences of bean flours to the primary BS; however, the largest BS retention was caused by HHP at 600 MPa. Bean materials preferentially delayed the release of chenodeoxycholate BS, which is probably related to BS micelle formation. These findings demonstrate that a combination of viscosity, molecular and compositional factors is triggering the BS-retention capacity of beans, and indicate the importance of evaluating contribution of individual bean components and as whole system.