Thermal Aggregation of Soy and Whey Proteins in Microemulsions for Simultaneous Purification and Functionality Creation

Protein aggregation during thermal processing presents challenges to manufacture beverages because of the possible protein gelation. A thermal pretreatment process was previously established in our group by dispersing a whey protein isolate solution as the water phase into a water-in-oil microemulsion, followed by thermal treatment. The thermal pretreatment induced the aggregation of proteins within the dispersed water droplets to form protein nanoparticles. The recovered nanoparticles lost gelation properties when redispersed and reheated. The work presented here was the extension to less pure protein preparations of soy protein isolate and whey protein concentrate. The produced protein nanoparticles did not form a gel at a solids content of 10% at neutral pH with 100 mM NaCl, while the control samples formed gels. The protein content of the nanoparticles was increased as a result of selective protein aggregation during thermal pretreatment, leaving non-protein contents in the microemulsion template. The selective aggregation was further verified by the reduced lactose content in whey protein nanoparticles. This work demonstrated the applicability of the developed thermal pretreatment process to less pure samples. Further, the technology may be integrated with the protein recovery process (from cheese whey and soy protein extract) to reduce the overall production cost of protein ingredients, while creating novel functionality.