Food Protection Trends - April 2009 - 214

TABLE 2. Tests commonly performed on raw milk samples Tests for certain pathogens considered to be the most dangerous, which include: Salmonella, E. coli O157:H7, S. aureus, and L. monocytogenes Cattle are also vaccinated against brucellosis and tested for tuberculosis and Johne’s disease (paratuberculosis) Specific pathogens Somatic cell count Presence of leukocytes (white blood cells) in milk, which is an indication of whether the dairy herd is infected Should be equal to or less than 200,000 cells/ml Indication of unsanitary production practices and/or mastitis A count of less than 100 CFU/ml is considered acceptable An indication of overall cleanliness of milking equipment Determines the numbers of visible individual or tightly associated clumps of bacteria in 1 ml of milk incubated at 90°F for 48 hours Standard plate count should be equal to or less than 5,000 CFU/ml Coliforms Standard plate count Drug or antibiotic residues Used for treatment of mastitis and for disease therapy, but can be shed in milk Commonly used drugs/antibiotics include penicillin, oxytetracycline, cephapirin, amoxicillin, cloxacillin, and gentamicin Cattle should be 100% drug/antibiotic residue-free Preliminary incubation Lab pasteurized count Sanitation inspection of milking system Monthly bulk tank cultures Sediment count Freezing point (Cryoscope) Rancidity Best measure of raw milk keeping quality and sanitation practices on farms Preliminary incubation count should be equal to or less than 10,000 CFU/ml Levels in raw milk should be less than 250–300 CFU/ml Commonly performed every 6 months Identification of equipment bacteria, mastitis, and potential environmental contamination Acceptable levels are less than 1.5 mg/gal milk Reading should be equal to or less than -.530° Horvet Acid degree value should not exceed 1.0 *Mastitis, an inflammation of the mammary glands, is caused by bacterial infection, trauma, or injury to the udder. Globally, it remains the most common and most expensive disease affecting dairy cattle. symptoms (OR = 0.24, 95% CI 0.10 – 0.53) compared to non-farmers’ children (75). However, the generalizability of this study is questionable; unidentified confounding factors in the farm environment may have been responsible for the reduction of these symptoms. Furthermore, Perkin’s study was cross-sectional, which makes it difficult to determine a causal relationship because of the lack of a time component. Assertions regarding the destruction by pasteurization of immunoglobulin G (IgG), a protein found in blood and other bodily fluids of vertebrates that is used by the immune system to identify and neutralize foreign bacteria and viruses, are refuted by Kulczycki, who states that the receptor-binding ability of IgG is not destroyed, but rather enhanced, by pasteurization of milk (66). Another source of contention is whether unpasteurized milk causes lactose intolerance. Bifidobacteria are claimed to aid in alleviating the symptoms of this disease. Raw milk consumers are not protected against developing lactose intolerance, as this condition is caused by innate lactase deficiency, low dietary intake of lactase after childhood, or a variety of illnesses, including Crohn’s disease, celiac sprue, or Whipple’s syndrome (16, 79). Raw milk proponents claim that it is also probiotic, or contains beneficial bacteria, however, raw milk is not considered a probiotic food according to the Joint FAO/WHO Working Group Report on Drafting Guidelines for the Evaluation of Probiotics in Food (9). In order for the term “probiotic” to be applied to a particular food, it must meet certain criteria, such as passing a safety assessment, and no such assement has been conducted for raw milk. Research regarding reduction of proteins, vitamins, and minerals by pasteurization have revealed that only very slight reductions of these components are caused by pasteurization of milk. The major milk proteins, caseins, are essentially unaffected by pasteurization 214 FOOD PROTECTION TRENDS | APRIL 2009
Food Protection Trends - April 2009

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