Ultra-high temperature (UHT) treated milk or recombined milk using for cheese making has become often a problem to incomplete milk coagulation. The ability of enzymatic coagulation for milk has decreased via heat treated in higher temperature than pasteurization (low-temperature long-time: LTLT), heat concentration, and spray dry. This problem has restricted the choices some milks for cheese making. UHT and recombined milk have included calcium chloride 0.02-0.10 w/v% were reacted for chymosin coagulation at 35 or 45 ℃, for 20 or 40 minutes. In both case, milk coagulation was depended on reaction time, temperature, and concentration of calcium chloride. The prepared curd from UHT milk at 45 ℃, for 40 minutes with 0.06 or 0.08 w/v% calcium chloride was significantly higher curd viscosity to LTLT milk curd. Furthermore, recombined milk curd has made at 45 ℃, for 40 minutes with 0.08 and 0.10 w/v% calcium chloride was no significant deference to LTLT milk curd. Reduced ability of enzymatic coagulation with chymosin of milk was improved on changed to optimum temperature of the chymosin reaction, extend of the reaction time, and adding calcium chloride.
