The processing of milk and milk products.

Abstract

Unfortunately it is not possible to guarantee that all raw milk is free from pathogenic micro-organisms, even in countries where the standards of animal health are high. Although the national dairy herd in the UK has been nominally free from tubercolosis for many years, and from brucellosis since 1981, no system of testing can ensure that any one time, micro-organisms are not being excreted into the milk by some cows. Mastitis in cattle is widespread, and micro-organisms that cause mastitis may directly or indirectly affect humans. Streptococci is an example that may cause scarlet fever or septic sore throat, and staphylococci, if subsequently allowed to grow in milk or milk products, may produce toxins which are a cause of food poisoning. Milk may also be contaminated after it leaves the udder, by contact with infected humans or animals, or with unclean utensils. So processes such as pasteurization are used to remove these risks with the minimum effect on quality or nutritive value of the product.