Evaluation of Raw Milk Quality Tests

A study was done to evaluate raw milk quality tests in an attempt to answer some questions regarding values or standards by which milk acceptance is determined. Initially, of 315 individual producer samples, 226 (72%) had proteolytic psychrotrophs. More than 90% of these psychrotrophs were of the genus Pseudomonas . All samples were obtained from four dairy companies processing milk in Georgia. One dairy had individual producers whose milk samples contained a large percentage of thermoduric psychrotrophs. "Bitter" flavors were more prevalent in samples collected from this dairy than in samples from the other three dairies. The degree of measurable proteolysis (Hull value) was directly correlated with the incidence of the naturally occurring "bitter" flavor. The mean Hull value for milk from this dairy (30.62 μg/ml) was 12-14 μg higher than the other three means. The mean Hull value for the "bitter" samples was 46 μg/ml.