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General Food Safety

Can I sell raw milk? Can I make butter out of pasteurized milk?

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Raw (or unpasteurized) milk has been documented as a causal agent for foodborne disease outbreaks due to the following pathogens: Coxiella burnetti (Q fever), Escherichia coli 0157:H7, Salmonella, Streptococcus pyogenes, and Campylobacter jejuni. Given this information, one should not drink raw milk because it could be unsafe. The only way to determine if the milk is safe is to determine the bacterial count of a sample. In fact, the milk we purchase in the grocery store has to meet specific bacterial standards before it can be pasteurized and used for fluid milk consumption. Nobody performs this service free-of-charge. Pasteurization is simply a process to rid the milk of any disease-producing organisms it may contain and to reduce substantially the total bacterial count for improved keeping quality. For years pasteurization time/temperature guidelines (143 F for 30 minutes) were designed to destroy Mycobacterium tuberculosis, the bacterium that can transmit tuberculosis to humans. In recent years, the pasteurization time/temperature has increased to 145 F for 30 minutes in order to destroy Coxiella burnetti, the source of Q fever. Therefore it is always recommended to pasteurize milk before consumption. Butter prepared from unpasteurized milk can be equally unsafe. Butter that one buys at the grocery store is made from milk fat, usually in the form of cream. The cream is pasteurized at a somewhat higher temperature than for pasteurizing milk because the high fat content has a slight protective effect on bacteria. The following article - "How Do You Like Your Milk?" authored by Loretta Robichaud, presents a concise summary about the pathogens associated with raw milk. It was Louis Pasteur who first made use of heat treatment as a method to eliminate the spoilage in beer and wine in 1871. The scientist discovered that the use of heat in just the right combination, of level and duration, could be used to kill organisms that spoil the product. The key was to kill the organisms but not to alter the taste of the product. This practice is still used today and for the dairy industry, pasteurization as a milk treatment is of paramount importance. Currently, fluid milk is pasteurized by a high temperature of 72 Celsius for a short time of 15 seconds (HTST) pasteurization method. It was also determined that pasteurization times should vary depending on the product. For example, creams and ice cream have higher heat treatments than processed fluid milk due to their increased viscosity. Milk was initially pasteurized to eliminate a very serious disease of this century, tuberculosis. The objective of pasteurization today is to provide a food product that is free of pathogens or disease producing organisms and thus safe for consumption. Pasteurization destroys all pathogens and a large percentage of the remaining non-pathogenic bacteria. The milk is gradually cooled down after pasteurization, preventing the growth of surviving organisms and extending the shelf life of the product. The concern over these few remaining organisms pales in comparison to the potential health risk associated with organisms from an unpasteurized (raw) milk product. Raw milk can include a wide variety of organisms, harboring any of the following. Salmonella, Listeria monocytogenes, Campylobacter, Yersinia enterocolitica, Enteropathogenic, Escherichia coli, Staphylococci, Staphylococcus aureus, Streptococcus, Streptococcus,, agalactiae, Brucella, Corynebacterium diptheriae, Coxiella burnetti, viruses, and mycotoxins. Some of the more serious of these raw milk vehicles of infection include: * Salmonella, which can contaminate the raw milk supply by contact with feces, or even from contaminated feed and water sources. The most severe infection can potentially result in death. * Listeria monocytogenes is an environmental contaminant that can lead to meningitis. Contaminated silage is the major transmission vehicle. It is even sometimes referred to as "silage disease." Once ingested, this organism can become part of the infective cycle. * Campylobacter causes acute bacterial gastroenteritis in humans. The intestinal tract and the bovine's udder are potential reservoirs. * Yersinia enterocolitica is indigenous to the gastrointestinal tracts of dairy cattle and therefore can also be found in raw milk. It has the potential to cause abdominal disorders and arthritis in adults, plus gastroenteritis or pseudoappendicitis in children. * Escherichia coli also contaminates raw milk from exposure to feces materials. The effect of the organism is very unpleasant with severe diarrhea and even causing kidney failure in the most extreme cases.

In studying the potential health risks associated with the consumption of raw milk, it startling to realize that some individuals still consume milk in this untreated form.

PREPARED BY: Angela M. Fraser, Ph.D., Associate Professor/Food Safety Specialist, NC State University in July 2004

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