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United States Department of Agriculture

Agricultural Research Service

Research Project: MICROSTRUCTURED AND HEALTH-FUNCTIONALIZED FOOD PROTEINS

Location: Dairy and Functional Foods

Title: Physical properties of mixed dairy food proteins

Authors
item Onwulata, Charles
item Thomas-Gahring, Audrey
item Phillips, John

Submitted to: Food Science and Technology International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 30, 2012
Publication Date: N/A

Interpretive Summary: Many foods such as yogurt or lunch meats may contain different types of proteins for the purpose of improved binding, flavor or mouthfeel. The problem is that different types of proteins do not mix well and sometimes act against each other resulting in poor food quality. Our research showed how to combine milk proteins with egg albumin, soy protein, and fish protein isolates in ways that improve the richness and thickness of foods. Our conclusion is that a right balance is needed if milk is to be mixed with egg proteins to create improved food mouthfeel. Dried egg white is the best protein to combine with milk proteins.

Technical Abstract: Mixed food protein gels are complex systems, which changes functional behaviors such as gelling properties and viscosity depending on the miscibility of the proteins. We have noted that differences in co-solubility of mixed proteins created unique network structures and gel properties. The effects of blending food proteins step-wise into calcium caseinate (CC) or whey protein isolate (WPI) adjusted to pH 2.5, 6.8, and 9.0 at 25C and 60C on solubility, viscosity, and gel structures were determined at their respective optimal soluble concentration level. The respective protein slurry viscosity and their optimal soluble concentration at 25C were: CC (1115.8 cP/15 wt percent), EA (175.2 cP/35 wt percent), FPI (2207.4 cP/30 wt percent), SPI (2531.5 cP/10 wt percent), and WPI (161.2 cP/35 percent). In mixed protein systems, for example, combining CC or WPI with EA, at the soluble protein level of 15 g/100 g, viscosity values were reduced: CC/EA (10:5 wt percent) 535.1 cP and WPI/EA (10:5 wt percent) 8.7 cP. Scanning electron microscope imaging revealed changes in protein aggregation clusters during heating of CC, EA, and WPI. These results suggest that some proteins such as EA may act synergistically to increase viscosity and FPI may act antagonistically to reduce viscosity.

Last Modified: 8/21/2014