β-Glucan Interaction with Lentil (<i>Lens culinaris</i>) and Yellow Pea (<i>Pisum sativum</i>) Proteins Suppresses Their <i>In Vitro</i> Digestibility

Abstract

In this study, β-glucan interaction with lentil and yellow pea proteins and the effect on <i>in vitro</i> protein digestibility were investigated. Proteins were mixed with β-glucan at mass ratios of 1:0.5, 1:1, and 1:2. The interaction between β-glucan and the proteins was demonstrated by the decrease in transmittance and surface charge and the increase in particle size of the complexes. Bright-field microscopy showed the formation of aggregates between the biopolymers, although increased molecular size was not observed by discontinuous native polyacrylamide gel electrophoresis. Fluorescence microscopy indicated that β-glucan formed aggregates with lentil proteins, while the interaction with yellow pea proteins appeared as distinct phases of protein within the β-glucan network. The <i>in vitro</i> protein digestibility of lentil and pea protein decreased by 27.3 and 34.5%, respectively, in the presence of a β-glucan mass ratio of 1:2. The findings confirm the possibility to modulate protein digestibility by changing the physical characteristics of a food matrix.