Raw cowmilk microflora: diversity and influence of conditions of production

The microbial composition of 158 raw cow milk samples taken from 27 farms l ocated in the French Alps area was determined. Microbial analyses included the total mesophilic aerobic bacteria count as well as numeration of some u seful cheesemaking microorganisms ( lactic acid bacteria, halophilic bacter ia, propionic acid bacteria), spoilage bacteria ( Pseudomonas, enterobacter iaceae, Clostridium spp.) and some of the pathogenic bacteria ( coagulase p ositive staphylococci, Escherichia coli). Milk samples were of good overall microbial quality ( mean value less than 10 000 cfu.mL(-1)) and had differ ent contents of useful cheesemaking microorganisms or spoilage bacteria. Fi ve different groups of milks were then separated according to their total c ount and to their relative contents in useful cheesemaking and spoilage mic roorganisms. When incubated at 37 degreesC for 24 h without any starters ad dition, milks of the different groups did not have the same ability to prod uce acid and to coagulate. At the farm level, milk suppliers practices were studied. Farmers differed by their way of washing the milking equipment an d by their pre-milking and post-milking udder preparation. Combination of t hese practices influenced the microbial load and composition of the milk pr oduced.