Optimization of the milk pasteurization and the curd cutting moment for artisanal fresh enzymatic cheese

Abstract

In Chimborazo-Ecuador a fresh enzymatic cheese is handmade produced from whole batch pasteurized milk at very high and variable temperatures (80 to 85 oC); the short clotting time also varies according to the cheese maker’s criteria, with low cheese yields and also very bad recovering of the milk components. This work objective was to determine the optimum milk thermal treatment parameters and the optimal curd firmness at the cutting moment, for the maximum technological efficiency. In the experimental part it was determined density, total solids, fat and proteins in milk, as well as humidity, fat and proteins in the obtained cheeses; a factorial design type Box-Behnken was applied, in which the independent variables were the milk pasteurization temperature (63 or 70 oC), the retention time in tank (15 or 30 min) and the curd firmness, measured with a portable penetrometer, at the cutting moment (1,7 or 2,1 cm). As objective or answer variables were taken the cheese yield and the recovering of milk components (total solids, fat and casein), measuring the processed milk volume and the mass of obtained cheeses in each production. It was concluded that the optimal milk pasteurization temperature was 66 to 67 oC with 15 to 30 min of retention time and that the optimum curd firmness at 35 oC, measured as penetration degree in the cutting moment, was 2,1 ± 0,1 cm; consequently the cheese yield was 12,52 % and the casein recovering 87,79 %, both indicators notably higher than the actual ones.