Microbiological and chemical quality of raw milk in New York State

Between December 1993 and January 1996, samples of raw milk from bulk tanks were collected by licensed milk haulers at the time of pick-up from 855 randomly selected farms in New York State (representing approximately 10% of all dairy farms in the state). The milk was examined for microbial and chemical qualities. Bacterial numbers were determined by standard plate count, laboratory-pasteurized count, coliform count, heat-resistant spore-forming psychrotroph count, aerobic spore count (mesophilic), rapid psychrotrophic count, and preliminary incubation count. The frequency distributions for these counts are presented. Paired correlation analyses between the microbiological parameters showed low correlations between test results; no correlation coefficients were > 0.8. The four highest positive correlation coefficients were found between standard plate count and rapid psychrotrophic count (0.7685), rapid psychrotrophic count and preliminary incubation count (0.6648), standard plate count and preliminary incubation count (0.5800), and aerobic spore count and laboratory-pasteurized count (0.5393). All other correlation coefficients were < 0.5. Milk freezing points and acid degree values were determined for all samples. Frequency distributions for these results are also presented.