Quality and stability of the natural yogurt produced from milk condensed with whey protein concentrate

Increase of dry substances in the processed milk, made by introducing various milk protein agents, has an influence on the properties of produced yogurt and its shelf life. This study examined the effect of adding 5% of powdered skim-milk and whey protein concentrate, and their mixtures in proportions 4:1 and 3:2, on quality and stability of natural yogurt. Titratable acidity was determined and active acidity, apparent dynamic viscosity and syneresis susceptibility were measured in yogurts directly after production, and after 7, 14 and 21 days of storage in temperature 8±1 °C. The produced yogurts were assessed organoleptically. Introduction of 5% addition of powdered skim-milk with whey protein concentrate mixed in above mentioned proportions resulted in essential increment of apparent dynamic viscosity and reduced syneresis susceptibility in the yogurts, comparing to separate use of the both components. These yogurts were also indicated as the most desired.