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

Chapter 6 – Safety and quality 261
A range of government controls can be applied to prohibit a certain practice or use
of a substance or regulations can be put in place that set maximum levels for specific
substances (e.g. dioxins, aflatoxin M 1 ), MRLs for residues of pesticides and veterinary
drugs or establish microbiological criteria for microbial pathogens. Guidance
and rules for good hygiene practice and the application of the Hazard Analysis
Critical Control Point (HACCP) system where appropriate throughout the chain
are important control measures.
Achieving a safe final product from raw milk to the point of consumption will
require a combination of control measures that together should achieve the appropriate
level of health protection. Preventive and control measures will not necessarily
be the same in all countries or production environments – they need to be
appropriate to the level of assessed risk, local production and processing procedures
and the differing characteristics of milk from various milking animals. For example,
many countries rely on controls other than an organized heat-treatment step such as
pasteurization: in East Africa, for example, milk produced by the smallholder sector
and sold through informal channels is generally boiled by the consumer before
drinking. This is effective for killing most pathogens; however, if the consumer is
unaware of the potential dangers of unpasteurized milk or forgets or chooses not
to boil the milk they may face higher risk of food-borne illnesses. Other control
measures can also be put in place, including a shorter chain from producer to final
consumer or the practice of the consumer purchasing smaller quantities as and when
needed (Grace et al., 2008). Farm practices should ensure that milk is produced by
healthy animals under acceptable conditions for the animals and in balance with the
local environment. It is important that control measures are applied during both
primary production and processing to minimize or prevent the microbiological,
chemical or physical contamination of milk.
A general distinction can be drawn between the types of control measures used
for microbiological hazards and those used for chemical and physical hazards. In
addressing microbiological hazards it is essential to prevent unhygienic practices
and conditions in the production, processing and handling of milk and milk products.
Minimizing the initial microbial load in milk and prevention of the growth
of micro-organisms are key to ensuring the safety of milk and dairy products.
The initial microbial load significantly impacts the performance (e.g. reduction in
amount or number) required of the microbiological control measures applied during
and after processing. Some issues that may influence the microbiological load
include herd size, distance from collection centre to dairy, temperature of the milk
when it reaches the dairy plant or market, presence or absence of a cold chain, and
duration of transportation.
Although pasteurization may reduce numbers of micro-organisms in milk, it is
not a substitute for good hygiene practices, especially as milk may be consumed
raw. On occasion pasteurization may not destroy all pathogens in the milk, especially
if it is not done properly (i.e. required time and temperature not followed).
To be effective, pasteurization does require a cold chain from the time the product
is pasteurized until it is consumed. As this can be challenging in many countries,
alternative methods such as the lactoperoxidase (LP) system may be used (Box 6.4).
Furthermore, where pathogens enter dairy plants in contaminated raw milk the
pathogens can persist in the plant in biofilms and contaminate subsequent batches of