• Oat β-glucan could reduce the minimum gelling concentration of pea protein gels • The microstructure of mixed oat β-glucan:pea protein gels was phase separated • The effect of oat β-glucan on the textural properties differed per pea protein isolate • CLSM analysis and an isostress model predicted water distribution in mixed systems Adding dietary fibres to proteins can enhance gelling, making it a promising approach to improve the structure for clean-label, plant-based foods. Various fibres may induce this effect, but the general applicability in protein gels is unclear. In this study, a commercial oat β-glucan rich ingredient (BGL) was added to heat-set pea protein gels to investigate the impact on gel characteristics, and whether the effects are general. Two commercial yellow pea protein isolates (PPI), PPI-A and PPI-B, were selected and had similar characteristics. Upon BGL addition, the microstructure of both PPI:BGL gels became micro-phase separated, but differences in gelling improvements were observed among the PPIs by uniaxial compression testing. With 5 wt% BGL addition, the Young’s modulus maximally increased 24-fold for PPI-A and 8-fold for PPI-B, and the fracture stress increased 14-fold and 2.5-fold, respectively. The minimum gelling concentration decreased by 3 wt% for PPI-B and 4 wt% for PPI-A. Corrected for dry matter content, gel improvements were less, indicating some effects stem from increased dry matter. Combining the results from protein dispersibility, water holding capacity, microstructure analysis (CLSM), and water distribution analysis (isostress model) revealed that the enhancements for PPI-A:BGL gels were caused by a higher effective protein concentration of the continuous gel microstructure. This supports the hypothesis that PPI-A allowed more water migration to the BGL-rich phases, thereby increasing the effective protein concentration. Thus, differences in water distribution are key to enhanced gelation of the two seemingly identical PPIs.
Janssen et al. (Fri,) studied this question.