Effect of acidification of whey protein-free precheese retentate on viscosity increase at different concentrations

The effect of acidification of whey protein-free milk retentate on the viscosity of retentate at different concentrations was studied. It was observed that the viscosity of retentate increased exponentially with increasing concentrations. The acidification of retentate (pH 5.75) before microfiltration decreased viscosity significantly and this decrease was more obvious at higher total solids concentrations of retentate. It was observed that the viscosity decreased as a function of pH during acidification of concentrated retentate with 370 g kg−1 total solids. Statistically significant and considerable decreases in viscosity were observed over a small pH decrease from 6.5 to 6.1. A statistically significant decrease in viscosity was also observed when the pH was decreased from 6.1 to 5.6. A decrease in pH of the retentate from 6.5 to 6.1 or from 6.1 to 5.8 decreased the viscosity significantly when the total solids were above 450 g kg−1.

► Effect of pH on viscosity of milk concentrate. ► Viscosity decreased as a function of pH. ► Effect of pH was more obvious in high total solids. ► Viscosity decrease with acidification may be of value in processes by which cheeses are made from full concentrated retentates.