Pasteurisation: an overview
by Gerhard Venter
Part 1.
Concept and methodology
Pasteurisation is attributed to a French scientist, Louis Pasteur. He applied heat treatment, followed by cooling, to milk in an attempt to extend the storage life of milk and prevent milk from transmitting potential disease to users. Raw milk was known to carry microorganisms that naturally sour the milk over time. This development spilled over to the preservation of many other foodstuffs and is not restricted to the application of heat.
A method called batch pasteurisation was initially employed. Milk in a container, which could be heated, was warmed to a specific heat below boiling point while being slowly agitated to expose all particles to the heated surface of the container. This heat was maintained for a specific period. Thereafter, the milk was cooled as rapidly as possible and stored refrigerated. This method is still applied for small batches, but obviously limits production time severely. To make the method efficient, a temperature of at least 62°C had to be reached and maintained for 30 minutes. This is also referred to as LTLT (long-time low temperature) pasteurisation.
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