Effects of polymerized whey protein prepared directly from cheese whey as fat replacer on physiochemical, texture, microstructure and sensory properties of low-fat set yogurt

The aim of this study was to investigate the effects of polymerized whey protein (PWP) prepared directly from cheese whey on physiochemical, texture, microstructure and sensory properties of low-fat set yogurt. The Cheddar cheese whey was subjected to a sequential processes, including pasteurization, pre-filtration, micro filtration, ultrafiltration, and electrodialysis, to obtain a concentrated whey solution with similar to 10.0% of protein content and 90% of salt removed. The majority (similar to 72%) of particle size distribution of PWP (70 degrees C for 10 min, pH 7.0) prepared directly from whey was in the range of 1-3 mu m. The PWP (1.4% protein, w/w) was added to skim milk as fat replacer. The texture, apparent viscosity, and sensory properties of the yogurt samples were analyzed in comparison with full-fat (3.0% fat, w/w), low-fat (1.0% fat, w/w) and non-fat (0% fat, w/w) yogurts. The nonfat yogurt incorporated with PWP (1.4% protein, w/w) had comparable sensory and textural characteristics to the low-fat (1.0% fat, w/w) yogurt. PWP prepared directly from whey through membrane separation technology can be used as a fat replacer to develop low-fat yogurt with desired characteristics. PWP might be used as a natural and economical ingredient for formulation of low fat fermented dairy foods.