No seasonal effect on culturable pseudomonads in fresh milks from cattle herds

Abstract

Freshly drawn raw milk from 37 single herds on farms manufacturing raw cow cheese under the Protected Designation of Origin (PDO) label were sampled over 13 mo for pseudomonad counts. Coliforms, somatic cells, and coagulase-positive staphylococci were counted and total fat and protein contents measured. For pseudomonad counts, the overall mean value was 3.60×10(3) cfu/mL. We observed very high variation between different producers and within the same producers (average standard deviation 1.30×10(4) cfu/mL), but we did not detect a seasonal effect. The only statistical correlation with other milk quality parameters was with coliforms. A survey of milking practices and milking machine sanitation together with environmental and milk sampling for pseudomonad counts in 7 cheese workshops showed that no real negligence or error could be imputed to producers. The main problems were the presence of non-aeruginosa pseudomonads in potable water and a few isolated failures during the cleaning and rinsing phases of sanitation.