DAIRY PROCESSING: Introduction

Milk is a valuable nutritious food which, if untreated, has a shelf life of only a few days before it spoils. There are however, a variety of preservation techniques applied to milk to extend its shelf life to several weeks or months and also to change its qualities by developing different flavours and textures. For small-scale processing, it is not possible to attempt production of dried milk powder or UHT (Ultra-High Temperature) sterilised milk, but other dairy products are potentially suitable.



To preserve milk it is necessary to destroy or inhibit the action of enzymes and contaminating bacteria. Milk is a low-acid food which contains all of the nutrients required for bacteria to grow. It is therefore a potential cause of food poisoning if not adequately processed. In all dairy processing it is essential that full and proper hygiene precautions are taken to ensure the safety of the products.

The four main methods of preservation suitable for small-scale operation are:

• Cooling - to extend the shelf life of fresh milk by a day or two.

• Heating - (pasteurisation, sterilisation or concentration) to destroy enzymes and micro- organisms.

• Acidification - to inhibit spoilage or food poisoning bacteria from growing and also change the physical characteristics of milk.

• Separation - of the milk components.