EFFECT OF PASTEURIZATION AND MICROFILTRAT ION ON THE HYGIENIC QUALITYOF GOATS MILK AND ON SOFT GOATS CHEESES

The aims of this study were firstly to compare the reduction in contam inant flora when pasteurization (70 degrees C for 5 min) or microfiltr ation (1.4 mu m pore size) are applied to goat's milk, secondly the ac idification kinetics of both milks compared to that of raw milk, and t hirdly the development of contaminant faecal coliforms and staphylococ ci during the making and ripening of 2 types of goat's cheese: lactic and rennet curds. Pasteurization and microfiltration were found to sig nificantly reduce the contaminant flora in goat's milk. Staphylococcal flora were reduced respectively by 1.4 and 1.1 Log units (P < 0.001) and faecal coliforms by 1.4 and 1.0 Log units (P < 0.05) respectively. Development of contaminant flora during milk acidification at 22 degr ees C was inversely proportional to the initial level of lactic flora. Acidification rate was highest in raw milk, intermediate in pasteuriz ed milk and lowest in microfiltrated milk. Both pasteurized and microf iltrated milks allowed a higher development of contaminant flora than raw milk in the drained curds; these differences were also observed in 30-d-old ripened cheeses manufactured from the 3 types of milks. Past eurization and microfiltration are processes which guarantee a low lev el of staphylococci and faecal coliforms in soft goat's cheese but res earch into the optimal growth of lactic acid starter during ripening m ust be carried out, particularly for rennet curd cheese technology.