Physico-chemical, textural, microbiological and sensory properties of low-fat set yogurt containing whey protein concentrate and lutein pigment

In this study, lutein Pigment (0.07, 0.13 and 0.2 %w/w ) and whey protein concentrate (0.2, 0.3 and 0.4 %w/w) were added to the milk.  Qualitative characteristics of yogurt samples were analysed regarding physico-chemical, microbiological, textural and sensory properties over 21 days. Adding whey protein concentrate and lutein, lowered the level of synersis and acidity but increased the amount of dry matter, fat, viscosity and pH of yogurt samples. According to the results of microbe analysis, there was not any evidence of the growth of mold, yeast and coliform bacteria in the samples. In the case of sensory properties, adding whey protein concentrate and lutein, raised the scores of texture, mouthfeel evaluation and lowered the scores of appearance evaluation. Among all treatments, yogurt containing 0.2 %, w/w whey protein concentrate and 0.07 %, pigment lutein earned the best score with respect to overall flavor and quality acceptability.