Effect of soluble salts on properties of rennet coagulated milk

Abstract

In order to study the effect of sodium, calcium and phosphate on the properties of rennet coagulated milk, changes in rennet coagulation time (RCT), 10 min firmness (a₁₀) and time required to achieve 20 mm; firmness (k₂₀) were monitored using lactody-narnograph. The RCT and k₂₀ increased with an increase in sodium chloride concentration in milk as well as in UF-concentrated milk, the a₁₀ value on the other hand/ decreased with an increase in sodium chloride concentration. RCT and k₂₀ values initially decreased upon calcium addition and reached a minimum at 0.01 M calcium concentration. At high calcium concentration (0.54 M) RCT and k₂₀ were severely retarded a₁₀ was maximum at 0.012 M calcium chloride concentration and beyond this concentration it declined. However, with an increase in phosphate concentration RCT increased; a₁₀ and k₂₀ values remained almost unchanged upto the concentration of 0.65 g per litre of phosphate, but thereafter a₁₀ value decreased and k₂₀ value increased. Thus changes in the concentration of sodium, calcium and phosphate affected not only the rate at which coagulation occured but also the firmness of the curd.