Pasteurisation
Pasteurization is the first step in milk processing. It means heating every particle of the milk or milk product to a specific temperature for a specified period of time (63°C) for 30 minutes or 72ºC for 15 seconds).
This destroys the germs that would spoil milk and affect the consumer’s health. It makes the milk safe and healthy and the milk products can be stored for longer periods without getting spoilt.
Simple methods of pasteurisation
- Direct boiling
Many farmers pasteurise their milk by direct boiling. However, direct boiling is undesirable, because it leads to burning at the bottom of the pan and browning of the milk. Indirect heating is a better way to pasteurise milk. Place the pan containing milk inside a larger metal vessel containing water so that the water forms a jacket around the milk pan. Heat the larger outside vessel using an open flame or gas stove or electrical hot plate. When the temperature of the milk reaches the pasteurisation temperature keep it at that temperature for a specified time (e.g. 30 minutes at 63°C); then remove from the heater.
- Batch pasteurization; 63°C for at least 30 minutes. This is suitable for small-scale producers and farmer cooperatives.
- High temperature short time (HTST) pasteurisation: 72°C for at least 15 seconds. This is suitable for processing large quantities of milk, e.g. more than 250 litres at a time. It is applied in factories.
- Ultra-high temperature (UHT) heat treatment at 135°C. This is mainly used by big factories. It requires special machinery. UHT milk can be stored for six months even without refrigeration.
Advantages of milk processing
- Preserves milk and improves its shelf life
- Changes taste and creates appeal to consumers
- Provides regular income
- Improves nutrition
- Selling processed milk products is more profitable than selling fresh milk
- Generates employment
- Improves quality and safety
