Milk-and-Dairy-Products-in-Human-Nutrition-FAO

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Milk and dairy products in human nutrition
Table 6.5 (continued)
Cause Food category Country Timeline Outbreaks Cases
Chemical
contamination
Dairy products Australia 1995–2008 1 23
Melamine
Contaminated powdered
infant formula
China 2008 1 >54 000
Unknown Dairy products Australia 1995–2008 6 86
Source: Fegan and Desmarchelier, 2010; Oliver et al., 2009; EC, 2003; NSW Food Authority, 2009; WHO, 2000; WHO, 2008b;
Fretz et al., 2010.
The composition of many milk products makes them a good media for microbial
growth, and various processes have been developed over the centuries in part to
extend the shelf-life of dairy products and provide a more diverse range of foods.
However, these may themselves give rise to specific hazards.
The following examples illustrate the linkage between milk product and potential
food hazard:
• Pathogen loads may be low in well-made hard cheeses because of their relatively
low pH, relatively high salt content, curd heating, long maturation and
possible presence of bacterocins (Fox and Cogan, 2004).
• High-moisture, fast-ripening cheeses are more likely to harbour pathogens
than are low-moisture, slow-ripening varieties. Outbreaks of listeriosis have
been associated with soft cheeses.
• Powdered infant formula may contain Cronobacter spp. (an opportunistic
pathogen emerging as a public-health concern), which affects infants in particular,
with neonates (up to 28 days old) and infants under two months of age
at greatest risk (FAO and WHO, 2006a). Additionally, the reconstitution of
powdered infant formula under unhygienic conditions or with contaminated
water and prolonged storage at warm temperatures can lead to an unsafe
product.
• S. aureus, a pathogen found in milk in bulk tanks, can produce a heat stable
enterotoxin that causes food poisoning. A large-scale outbreak occurred during
June 2000 in Japan caused by consumption of low-fat milk produced from
skimmed-milk powder contaminated with S. aureus enterotoxin A (Asao et
al., 2003). Ice-cream mix can also provide the right conditions for the growth
of S. aureus.
• Non-pasteurized milk and inadequately pasteurized milk contaminated
with Campylobacter jejuni is a common source of this food-borne pathogen
(Fahey et al., 1995; Evans et al., 1996).
Increasing attention is focusing on the risks associated with the consumption of
raw milk and raw-milk cheeses; given that these products are not pasteurized or
subjected to processes equivalent to thermal pasteurization, alternative safety controls
are required. For example, high-moisture raw-milk cheeses are of considerable
concern although most of these have a low initial pH (4.6) and appear to be safe
(Fox and Cogan, 2004).