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.