Augmentation of faba bean globulin gelation with pre-aggregation

Plant proteins play crucial roles in the protein transition from the use of animal proteins to a more sustainable food production. During industrial plant protein ingredient production, thermal denaturation generally occurs, for instance, during the drying or sterilization of plant protein extracts. This can result in mixtures of native and denatured (and aggregated) plant proteins, or just fully denatured ones. The influence of denaturation on techno-functionality (e.g., gelation properties) of native plant proteins merits attention. This study took faba bean globulins (Fg) as an example, and investigated the effect of thermally induced pre-aggregation on the heat-set gelation properties of native Fg. All pre-heat treatments (95 °C for 10, 30 and 60 min) fully denatured Fg, causing heterogeneous protein aggregation, increasing the surface hydrophobicity by 2-3-fold, and only slightly lowering the protein solubility (by 3-10%). The two longer heating times increased the width of the protein particle size distribution and resulted in the formation of large insoluble protein aggregates. The 10 min heat treatment effectively improved the gelation abilities of native Fg, forming stiffer, more stretchable, more connected, and less heterogeneous gel structures that were self-supporting, compared to gels formed by native Fg. The larger Fg aggregates resulting from longer heat treatments acted as active fillers and enhanced gel stiffness, but their heterogeneity and the mixing with native Fg tend to increase the overall heterogeneity of the gel systems and weaken the gels. These findings suggest that protein denaturation does not necessarily limit the functionalities (e.g., solubility and gelation) of commercial plant proteins, but the heterogeneities of protein particle size and nativity could play a big role. This study could guide a novel design of industrial food processing to produce plant protein extracts with retained or improved gelation properties by controlling protein denaturation and degree of aggregation. • Preheating native faba bean globulins (Fg) induces aggregation of Fg. • A low degree of aggregation of Fg improved gelation properties. • These gels were stiffer, more stretchable, more connected, and less heterogeneous. • A high degree of aggregation produces more heterogeneous and weaker gels. • Degree of denaturation and heterogeneity of particle size are crucial factors.