The influence of the population of psychrotrophs in raw milk on the characteristics of natural yogurt

The influence of psychrotrophs in raw milk on the characteristics of natural yogurt was evaluated in this study. Product A was made from raw milk containing 7 ± 1 log CFU mL−1 of psychrotrophs, and product B with 3 ± 1 log CFU mL−1. The rate of proteolysis over 35 days was higher in product A, which showed greater syneresis and viscosity from the 14th and 28th days, respectively. At 35 days, product A had greater hardness and gumminess and less cohesiveness than B. Tasters detected differences between the yogurts, and the comments “more acidity” and “more consistency” about product B were associated with lower pH values and greater cohesiveness, respectively. Lactic acid bacteria populations and titratable acidity of the yogurts were not affected. Product A had higher levels of some Free Fatty Acids (FFA). In this way, the characteristics of Product A influence its consumption and purchase, causing economic losses for the industry.