Hybrid gelation behaviour of precision fermentation-derived β-lactoglobulin with plant proteins from various sources and fractionation routes

Combining novel and sustainable proteins offers new opportunities for food structuring. This study investigated the heat-set gelation of various plant protein concentrates individually, and when mixed with precision fermentation-derived β-lactoglobulin (BLG), including: commercial denatured faba bean protein concentrate (FBPCCD), commercial native FBPC (FBPCCN), commercial denatured pea protein concentrate (PPCCD), PPC lab-fractionated using isoelectric precipitation (PPCIEP) and PPC lab-fractionated using membrane filtration (PPCMF). Fractionation yielded 70 - 85% protein purity and minor compositional differences. DSC experiments confirmed the nativity of BLG, FBPCCN, PPCIEP and PPCMF. These concentrates had higher solubilities than their denatured counterparts. SLS and DLS confirmed more extensive aggregation for FBPCCD, PPCCD and PPCIEP than FBPCCN and PPCMF. SAOS rheology confirmed that the denatured FBPCCD and PPCCD formed softer gels than their native counterparts. The less aggregated and more soluble FBPCCN and PPCMF showed a higher gel firmness (G′) of 1.5 kPa and 5.0 kPa, respectively, than other plant proteins. BLG showed the highest G’ of 9.1 kPa. BLG addition in hybrid gels gradually increased gel firmness, especially with the native and less aggregated plant proteins. FBPCCN even showed a synergistic effect when combined in a 50:50 and 20:80 ratio with BLG. LAOS rheology revealed that increasing BLG levels typically increased the ductility of mixed gels. PPCMF deviated from that trend, likely due to microphase separation, which was consistent with the microstructures observed in confocal microscopy. Additional experiments using the thiol-blocking agent NEM in FBPCCN gels, and with mixtures of egg white protein and BLG mixtures, indicated that proteins which form disulphide bonds upon heating formed firmer gels when mixed with BLG. These findings suggest that plant protein nativity, solubility and aggregation state critically influence gel performance when mixed with BLG, and that disulphide bonding may serve as a predictor for synergistic gelation in mixed protein gels.