Pasteurization of Milk
It is defined as a process of preservation of the milk, where in the milk is heated to such temperature and for such a period of time so as to destroy all the pathogens in it and to preserve the nutritive value of it without changing the color, smell, taste flavor and composition.
Thus Pasteurization is the simplest, safest and cheapest and modern method of rendering the milk safe. It is an example of prophylactic ,(precurrent ) disinfection procedure.
Method of pasteurization
These are holder method, HTST method and UHT method.
Holder method (vat process, holding process): In this method milk is heated to 65c (145-150c)and maintained at this temperature for 30min and then suddenly cooled to a temperature below 5c. Rapid cooling prevent growth of the organism. It is a British method, slow method, recommended for small and rural communities.
High temperature and short time process (HTST) (flash process) method: In this method, milk is heated to 72c and maintained for at least 15 seconds and then rapidly cooled to less than 5c. It is an American method, rapid method and most widely used. Recommended for urban area to pasteurize large quantity of milk.
Ultra high temperature (UHT) process method: In this method, milk is heated in two stages. In the first stage, heating is done under normal pressure to 88c for few seconds, then in the second stage, it is heated to 125c under pressure for few seconds only.
In Pasteurization, 90 percent of the pathogens and lactobacilli are destroyed and not the spores.
After bottling, the milk is kept cold, untill if reaches the consumer, because with subsequent rise in temperature, bacteria are bound to multiply.
Comments
Manjit Singh
19-Mar-2021 01:48 PMvery good