Interaction of a bile salt (sodium taurocholate) with cationic (ε-polylysine) and anionic (pectin) biopolymers under simulated gastrointestinal conditions

Dietary fibers are known to have beneficial effects on human health, which is partially attributed to their interactions with components in the gastrointestinal tract. In this study, the interaction of model bile salts with anionic (pectin) and cationic (polylysine) food-grade biopolymers, and their electrostatic complex, was examined. Isothermal titration calorimetry and titration measurements were used to characterize the nature of the interactions between the biopolymers and bile salts. Analysis of isothermal titration calorimetry data showed a marked difference for the taurocholate-pectin and taurocholate-ε-polylysine complexes, suggesting that sodium taurocholate binds strongly to ε-polylysine, presumably due to the attraction of oppositely electrical charges. While, the interaction between sodium taurocholate and pectin seems to be dominated by hydrophobic forces. On the other hand, the interaction of sodium taurocholate with a mixture of the two biopolymers showed a behavior that combined the characteristics of the individual systems. These results may have important implications for the design of functional foods to improve human health and wellness.