Journal of Food Processing & Technology

Abstract

Whey Protein Concentrate as a Substitute for Non-fat Dry Milk in Yogurt

Berber M, González-Quijano GK and Alvarez VB

Whey is a liquid by-product produced during cheese manufacturing. Whey was once considered a waste product but it is converted to food ingredients through processing steps that include membrane filtration, heat or enzyme modification, and fractionation. These processes have made it possible to improve sweet whey utilization. Whey proteins have good nutritional properties and enhance the textural properties of food when they are used as ingredients. The objective of this study was to evaluate non-fat, low-fat and full-fat stirred style strawberry flavored yogurt formulated with whey protein concentrate 80 (WPC80) replacing non-fat dry milk (NFDM). Levels of total solid were adjusted to 14.8%, 15.7% and 17.3% for non-fat, low-fat and full-fat yogurts, respectively. Yogurts formulated with non-fat dry milk were used as controls for all fat levels. Batches of 17 pounds of yogurt at 0% fat, 1% and 3.25% fat were made by mixing milk with powdered ingredients in a liquefier and homogenized at 2,300 psi for first and 500 psi for second stage, respectively. Double stage homogenized yogurt milk was pasteurized at 92°C for 30 seconds. Following cooling, yogurts were fermented to a final pH of 4.5. Yogurts were analyzed for their chemical and physical properties following the standard methods of analysis. Sensory evaluation was done by descriptive method with hedonic and monadic scales by trained judges. Whey protein yogurts at all fat levels showed better water holding capacities (ca. 10%) than controls with increased hardness (ca. 20%) and viscosity (ca. 40%). Sensory results revealed that whey protein yogurts had higher flavor and overall liking scores than controls, while controls had better scores for the yogurts’ texture. Results showed that WPC80 is a good alternative to replace NFDM completely in yogurt. Whey yogurts had equal or greater quality than yogurt products made with NFDM.