Food Protection Trends - April 2009 - (Page 213) FIGURE 2. Average milk composition as percent of total volume FIGURE 3. Composition of non-fat solids in milk adopting these regulations. Raw milk and raw milk cheeses are not labeled “Grade A” because they are not pasteurized and do not meet the requirements specified in the PMO. OppOSING VIEWS According to the Centers for Disease Control and Prevention, since 1998, more than 800 people in the United States have become ill from consuming raw milk or cheese products made from unpasteurized milk (10). Raw milk proponents believe that pasteurization of milk diminishes the nutritive value of milk, causes pathogens to multiply, destroys immunoglobulin G antibodies, and causes lactose intolerance (85). They also maintain that pasteurization destroys proteins and polypeptides, including enzymes, such as lactoferrin, xanthine oxidase, lactoperoxidase, and lysozyme, as well as nisin; some of these are claimed to be necessary for calcium absorption (15, 44). It is also claimed that the pasteurization process causes allergic reactions, kills beneficial bacteria, and is associated with the development of arthritis (15, 44). Moreover, they praise unpasteurized milk’s richer flavor and claim that it is more nutritious and leads to stronger immune and digestive systems than pasteurized milk (15, 44). Review of the scientific literature has shown that there are no significant nutritional differences between pasteurized and raw milk (59). Milk is a nutritive source of lactose, proteins (casein and whey), vitamins (thiamin, folate, vitamin B12, riboflavin), minerals (especially calcium) and enzymes (Figures 2 and 3) (99, 101). The bovine enzymes naturally present in milk are reduced by pasteurization, but these enzymes are not used by humans to aid metabolism of calcium and other nutrients; enzymes naturally present in humans are used to digest and metabolize the components of milk. At present, there is no scientific evidence to substantiate the claim that there is an anti-arthritis factor present in raw milk or that any factor in raw milk enhances resistance against diseases. Vitamin D, which aids in the body’s absorption of calcium, is added to pasteurized milk, but is found in only minute amounts in raw milk (85). The creamier flavor of raw milk can be attributed to a perception of a higher butterfat content, as the fat particles have not been homogenized (treated so that the fat droplets are dispersed). Raw milk advocates have also claimed that two types of spore-forming bacteria (termed “heat-resistant pathogens” by raw milk advocates), Bacillus cereus and Clostridium botulinum, survive the pasteurization process. B. cereus can be eliminated through pasteurization at temperatures above 100°C, and the growth of C. botulinum in milk, though possible, is rare because milk is too aerobic to allow this organism to grow (100). Lactoperoxidase and bovine milk lysozyme, enzymes key to limiting microbial growth and spoilage, are described as being inactivated by pasteurization. Lactoperoxidase is not destroyed by minimum pasteurization standards (85) and Griffiths has reported that bovine milk lysozyme also survives pasteurization (50). Some raw milk advocates have stated that drinking unpasteurized milk on the farm during childhood can help abate allergic symptoms, such as allergic rhinitis and asthma. In a study by Perkin, farmers’ children who drank unpasteurized milk showed decreased asthma symptoms (OR = 0.67, 95% CI 0.49 – 0.91), seasonal allergic rhinitis (OR = 0.50, 95% CI 0.33 – 0.77), eczema (OR = 0.59, 95% CI 0.40 – 0.87), and atopic APRIL 2009 | FOOD PROTECTION TRENDS 213
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