Microbiological quality aspects of cow's milk at a smallholder cooperative in Turrialba, Costa Rica

Abstract

Some of the critical moments and factors influencing the hygienic quality of milk were investigated at a smallholder cooperative in Costa Rica from which all the members delivered milk to a processing plant. Twenty-two farmers provided data for this study. Milk from all lactating cows was examined with the California Mastitis Test (CMT). Apparent mastitic milk was processed for bacteriological investigation (BI). Additionally, milk samples were collected from storage containers for somatic cell count (SCC) and for BI. Out of the 22 farms 10 were selected for further study on the hygienic quality of the milk sampled at specific critical moments during handling, storage and after transportation to the processing plant. Point prevalence for CMT-positive samples was 21.8%, 36.6% and 28.4% for the months of June, August and October, respectively. The incidence rate for CMT-positive samples for this period was 27.8%. Eighty-three out of 126 milk samples taken from storage containers for SCC contained less than 400,000 cells/ml. Eight percent of the CMT-positive milk samples contained S. aureus. Twenty-eight percent of the milk samples from storage containers contained S. aureus and 79% of the samples E. coli. All milk samples from storage containers obtained at the processing plant had CFU counts exceeding 2.106 cells/ml. This milk was severely contaminated with bacteriological agents from environmental origin. Cooling of the milk was found to be inadequate. The udder preparation method, unclean milk equipment and the water used for cleaning purposes were the main sources of milk contamination.