Pasteurization

Pasteurization is one of the methods of preservation of products such as milk, alcoholic beverages etc. at higher temperatures. Pasteurization is defined as the process of heating products to a particular temperature and holding it at that temperature for a particular time till the pathogenic (disease causing) micro-organisms are destroyed causing minimum change in composition, flavor and nutritive value of products such as milk.

• There are two methods of pasteurization (of milk) in general use. One is low temperature holding (LTH) method in which milk is heated to 62.8°C (145F) for 30 minutes in commercial pasteurizers (or) large closed vats which are heated by steam coils, hot water jackets etc.
• The other method (i.e.) high temperature short time (HTST) method in which the milk is heated to 71.7°C (161F) for 15 seconds.

The heating is accomplished by electricity (or) hot water and requires a heat exchange system, which preheats raw, cold milk and cools the hot pasteurized milk. Please note that Pasteurization conditions are not sufficient to destroy thermo-resistant spores (reproductive part of microorganisms).  Thus, Pasteurization does not sterilize the products but kills only those organisms that grow most readily at low temperatures. The surviving organisms must be kept from multiplying by constant refrigeration.