What are the risks associated with the consumption of raw milk cheeses?
A few years ago, as I was studying for my first Food Safety diploma, the teacher conceded to me that she did not know much about dairy products and asked me if I could do a talk on the safety of pasteurized cheeses.
I was not very excited about the subject, not that pasteurized cheeses are all bad; many are made in an artisan manner and rather good. You may actually find some of these on www.rindwash.market, it is just there is no substantial difference between raw and pasteurized milk on the finished product.
What are the risks and benefits associated with consumption of raw milk cheeses?
Producers of raw milk cheeses have to reconcile multiple Food Safety demands.
They are very vigilant when it comes to the microbiological quality of raw material. Samples are analysed after milking to determine the biological diversity. More samples are analysed during making and then on the finished products, which subject to European legislation ( still in place so far ), must meet the sanitary standards in production output. Undeniable progress has been made to control contamination from production of milk. This results in increasingly stringent measures of hygiene in the implementation of a HACCP-type approach (Hazard Analysis Critical Control Point method and principles of management of food safety). The contribution of milk and dairy products poisoning in Salmonella, Staphylococcus aureus or Listeria, represents less than 6% compared to other products. S. aureus is the bacterial species most involved in foodborne illness due to dairy products but has never been responsible for deaths.
Raw, thermised and pasteurised milk share the responsibility for food poisoning incidents without significant differences. Since 1997, the number of cases of listeriosis has stabilized around 200 cases per year ( France produces more than 180000 tons of raw milk cheese per year) and affects more than 50% of people whose immune system is disturbed, pregnant women, elderly, newborn.
L. monocytogenes was detected more frequently in cheeses made from pasteurized milk (8%) than in raw milk (4.8%) (Rudolph and Scherer, 2001). In France, over a period of 10 years (1987-1997), 73 infections due to cheese consumption were recorded for 2 million tonnes of raw milk cheeses!
The most serious poisonings are often associated with technological processes or defective storage before consumption. The many benefits of raw milk cheeses consumption are linked to the diversity of microbial populations inhabiting the ecosystem cheese. Thus, more than 150 microbial species (bacteria, yeasts or moulds) have been identified in raw milk, each with its own balance in terms of species and strains (Callon et al., 2007, Delbès et al, 2007). The diversity of microbial populations in raw milk is the source of a wide variety of aromatic molecules, themselves the source of the diversity and richness of sensory raw milk cheeses (Montel et al, 2005). Biodiversity can not be reproduced during the seeding of pasteurized milk in which only a limited number of strains is inoculated which leads to a uniform sensory characteristics.
Microbial diversity in raw milk cheeses is an asset, it constitutes a barrier to pathogenic micro-organisms (Millet et al, 2006). It can inhibit microbial populations or species such as opportunistic pathogens by acidification, production of inhibitory metabolites (organic acids, ethanol, bacteriocins) or by nutrient competition. Epidemiological studies have shown that consumption of raw milk may provide protection against asthma and allergy (Waser et al, 2007). The consumption of fermented products with complex flora could improve the immune system (Moreau and Louis Vuitton, 2002) or limit colonization of the intestinal tract by some micro-organisms resistant to antibiotics (Bertrand et al, 2007). Exposure to micro-organisms in early childhood could prevent atopic disorders (Racila and Kline, 2005). Young children living on farms or in contact with animals have less sensitivity to allergens (Riedler et al, 2000).
I walked quite late when I was a baby, my first few steps were taken in a field where cows grazed. My first fall happened shortly after when I landed in cow dung!
Unashamedly, I still very much enjoy the smell of cow dung, that typical smell of the farm which one might smell on the surface of some raw milk cheeses. It does brings me back!