Cheesemaking 101: Pasteurization

Pasteurization
Pasteurization is the first step in almost all cheesemaking. It is a method of heat treatment invented by Louis Pasteur in the late 1800's to prevent the spread of diseases carried by milk and other foods, and involves heating the milk to 63 degrees Celsius and holding it there for 30 minutes. This level of heating has been determined to kill any harmful bacteria that may be in the raw milk. Of course, it also kills any beneficial bacteria, such as naturally occuring lacto-bacilli; but it is simple enough to add these back into the milk once it has been cooled, so this side-effect is not really a problem (although some would argue that the wide variety of culture strains present in the raw milk cannot easily be reproduced by a freeze-dried product).

The main argument against pasteurization is that it destroys some flavour compounds present in the raw milk, and causes some of the lactose to caramelize, both of which can have an effect on the flavour of the finished cheese. As a result, some people will go to great lengths to search out raw milk cheeses.

The law in Canada requires all cheese to be made from pasteurized milk, unless the finished cheese will be stored, before sale, for longer than 60 days at a temperature above 4 degrees Celsius. This is normal for hard cheeses, so it is possible to find this type of cheese made from raw milk in Canada. But a soft or semisoft cheese cannot be kept for this long, with the result that just about all Brie and Camembert type cheeses made in Canada are pasteurized. All of the cheeses made by Salt Spring Island Cheese are made with pasteurized milk.