As drawn from cow’s udder , milk seldom , if ever, is free from microorganisms; bacterial, molds, and yeasts are usually present in small numbers, among which the bacteria are most significant from stand point of quality and the transmission of food borne disease. The control of microbial activity in milk and milk products, especially the control of bacterial and bacterial growth, is the most important function in the handling and manufacturer of dairy products.Raw milk, when improperly handled, may undergo any of several adverse changes. It may become sour due to the growth of bacteria that produce lactic acid , or it may become foamy due to the growth of gas producing coli form bacteria or yeasts. Raw milk may also be subject to peptonisation (digestion of casein), the formation of rope (viscous polymer of sugars), and sweet curding, when bacterial growth is not controlled.
Dairy herds are tested for tuberculosis and tested for and vaccination for brucellosis, and most milk is pasteurized to prevent the transmission of a variety of food –borne disease. However, some pathogens may be survive the pasteurization process, possibly because they may be protected by fat in which they may become encapsulated.
Most, but not all, certified milk is pasteurized. However, certified milk must be produced from herds that have been inspected, tested, and found to be free form disease, and the milk must be drawn and handled under the best condition of sanitation. There are bacterial standards certified milk that limits the number and types of bacteria that may be present.
Microorganisms in milk
