Milk can be stored only for 3 hours at room temperature just after milking. The shelf life of milk can be increased up to 24 hours by cooling at 5°C. Its shelf life is further extended to 4 to 7 days by pasteurization. Milk shelf life can be extended up to few months when UHT treatments are given. Equipment and electricity required for pasteurization. To preserve milk for 6-12 months lactoperoxidase system is used without the requirement of equipments and electricity.
HISTORY OF PASTEURIZATION
IN 18th century the procedure of boiling of milk was being used to decline milk born infection causalities in infants. At the end of twenty century industrial community enhanced the milk production and availability led to epidemics of milk born infections. At that time common milk borne diseases were scarlet fever, typhoid fever, diarrhea, septic sore throat and diphtheria. These diseases were almost removed with the industrial application of pasteurization, in union with upgraded management applications at dairy herds. In 1939, milk goods were identified as source of 26% infections of food borne diseases but now by using the process of pasteurization of milk and milk products this value has been decreased up to 1 percent.
PASTEURIZATION
The process of warming of every milk particle to at least 63°C (145°F) for 30 mint or 72°C (161°F) for 15 second or to any other appropriate time temperature combination. The milk is instantly cooled to 5°C (41°F) or below after pasteurization treatments. By pasteurization undesirable microbes and pathogens are destroyed existing in milk to enhance the shelf life of milk. To treat the milk a variety of pasteurization methods used are:
1. Batch pasteurization / low temperature long time pasteurization (LTLT)
2. High temperature short time pasteurization (HTST)
3. Ultra high temperature treatment (UHT)
Post pasteurization contamination.
After the pasteurization microorganism get chance to re-enter in to pasteurized product via contaminated equipment or workers.
From raw milk, air and moisture pathogenic microorganism can be introduced to dairy environment which causes health and economical losses. The existence of any vegetative pathogen implies post pasteurization contamination but spore formers are likely to enter through raw milk.
PACKAGING
Packing material must be kept in dry place and away from manufacturing unit in non-toxic clean and hygienic place.
While packing one should avoid the re-entry of pathogens or undesired microorganism in processed products. Avoid the contamination in processed products until product reaches to consumer.