Steven Murphy of EAS Consulting Group, Alexandria, Va., provided an overview at the American Dairy Science Assn.'s annual meeting on the current science related to regulatory standards used as indicators of conditions considered public health risks for grade A milk and milk products.

Requirements for grade A raw milk include temperature (≤7°C), bacterial limits (≤100,000/mL produced), drug residues (not found) and somatic cell count (SCC) limits (≤750,000/mL). While lower temperatures are ideal, Murphy said limited storage time reduces public health risks.

Although exceeding limits for bacteria and SCC indicate deficiencies in production practices and potential quality effects, from a public health perspective, Murphy said no need for more stringent standards was found, assuming that a 5-log reduction of pertinent pathogens is sufficient.

Somatic cells are not associated with public health but may present a negative image, according to Murphy. He noted that the public health impact and testing requirements for drug residues is not without debate.

Bacterial count limits of pasteurized milk products provide no information on potential pathogen contamination and are often performed without consideration for microbial growth over shelf life, Murphy said. Coliform bacteria historically used as indicators of post-processing contamination (PPC) are unacceptable at any level; their absence, however, does not confirm that PPC has been prevented.

According to Murphy, alternative microbial methods are needed. ALP test results used to indicate proper pasteurization typically are <100mU/L, so milk with a result of 300mU/L, while acceptable, would likely contain raw milk or be underpasteurized.

“It is time for change for some indicators, and further research is needed, especially with pasteurized milk products,” Murphy said.