Colloidal dispersion of casein micelles and pea protein via homogenization

Abigail Krentz
Graduate (MS)
Rafael Jimenez-Flores
Food Science and Technology

The dairy industry struggles to maintain the attention of consumers in midst of declining fluid milk sales. However, current trends create an opportunity to incorporate plant protein with milk protein, for potential applications to produce a high-protein, multi-sourced, functional ingredient. Plant proteins can be challenging to use in food because of their low solubility and undesirable off-flavors. However, casein micelles provide a particular system optimal for protein blending along with high sensory acceptability. The objective of this study was to create a stable colloidal dispersion of milk protein combined with pea protein with two goals: 1) to improve the solubility of pea proteins in aqueous solution, and 2) to preserve or improve the functional properties of milk protein, such as coagulation ability, emulsion capacity, and foaming capacity. Three blends were created with varying ratios of casein-to-pea protein (90:10, 80:20, 50:50). The mixtures were subjected to three cycles of homogenization using a bench-top GEA 2-stage homogenizer at 4,000 psi maintaining 4-10C and then pasteurized at 63C for 30 min. The resulting blends were homogenous liquids, with no precipitate formation. Protein profiles obtained via RP-HPLC analysis and SDS-PAGE showed that some of the various pea proteins had incorporated with the casein micelles. The pea proteins that interacted with the caseins were isolated and sequenced. The amino acid sequencing indicated that vicilin, an insoluble pea protein, was identified as the main protein incorporated within the caseins. These results support our hypothesis that cold-temperature homogenization can successfully be used to create a colloidal dispersion in which insoluble pea protein may be incorporated with casein micelles in an aqueous solution. Additionally, upon coagulation of the liquid blends, protein gels were formed with textures similar to commercial queso fresco, and hard tofu. Further sensory analysis will need to be conducted. This research highlights a promising application for other plant proteins to be utilized within the dairy industry and can help drive future product innovation while also meeting current processing conditions and consumer demands.