Understanding Plant Protein Chemistry and Functionalities Towards the Construction of Better Meat Analogues

Plant proteins are rising as promising alternatives to animal food proteins, with increasing public recognition of their sustainability and health benefits. In this study, the plant proteins sourced from soy, yellow pea, and wheat are classified into cold swelling or heat swelling types through various raw-material tests, and these proteins were blended in varying cold-swelling: heat-swelling ratios (0:100 to 90:10) and extruded to produce texturized vegetable proteins (TVPs). The quality and texture attributes of these TVPs were characterized, and both the raw materials and TVPs were analyzed to understand structural and functional transformations of the proteins during texturization.

Our findings revealed that higher proportions of cold swelling protein in the formulation led to TVPs with greater porosity and water-holding capacity, but reduced bulk density, resulting in a decrease in the hardness of the formulated patties and an increase in consumer liking. The texturization process led to a decrease of free thiol and free amino groups in the proteins, and a reduction in protein surface hydrophobicity. Although the TVPs were insoluble in phosphate buffer, adding certain chemical reagents significantly improved protein solubility up to 80%. The solubility results in various tailored buffers indicated that the disulfide bond was more crucial than hydrogen bonding or hydrophobic interaction during protein texturization. The water holding capacity decreased, while the oil holding capacity increased slightly for the TVPs compared to the raw materials. All the TVPs showed limited emulsification, foaming, and gelation properties. In vitro digestibility of the TVPs either slightly increased or remained unchanged compared to the raw materials.
Overall, this study advances our understanding of protein-protein interactions and the functional changes occurring during the texturization process. These insights are valuable for enhancing the future production of better meat analogues and expanding the applications of plant proteins.