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Milk is one of the most important products for human consumption. Its high quality is vital, and cooling is one of the most efficient and effective ways to maintain milk's freshness. The demand on milk producers is to produce milk with a composition that meets the needs of consumers.
All chemical processes depend on temperature. At lower temperatures, chemical processes are slowed down and chemical spoilage is delayed. Milk contains several nutrients that are necessary for the life of all living beings. It is also the perfect growing medium for micro-organisms, although at 4 °C micro-organisms cannot duplicate and the microbiological spoilage of milk is avoided. After having followed the right milking and hygienic procedures, quickly cooling milk to 4 – 3 °C is the best way to avoid microbiological growth and chemical changes.
In the first human societies, snow and water were used for cooling food. Later, the theory of cooling by evaporation was developed and practised for a long time. Old Egyptian nations evaporated water in porous vases to cool their food.
Cooling media such as refrigerants (food cooling) and ammoniac (non-food cooling) are used in present-day refrigeration equipment. In the future, these cooling media will be replaced by others that have a less negative impact on the environment.
The aim of this booklet is to introduce the reader to the complex, but also fascinating process of milk cooling. We will learn the cooling principle, the reasons for cooling and the different ways of cooling milk. This book may not answer all your questions, but it can be a beginning for further reading and learning.
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