Most cow’s milk bought in shops is homogenised.
How Homogenisation Works
Homogenised milk is produced by forcing milk through a small passage at high speed. This breaks down the fat globules in milk into much smaller ones and creates a stable fat emulsion. This avoids – (remember cream at the top of your doorstep milk?) having that collar of fat, or cream at the surface, so that it is evenly distributed throughout the milk. Other advantages of homogenisation are a more evenly distributed flavour as the fat is dispersed through the milk, and a longer shelf life.
The Effect on Some People: Lactose Intolerance
The disadvantage of homogenisation is that the process breaks up the normally large fat particles into tiny ones and forces the fat to form tiny molecular clusters so that they cannot reform, instead, staying suspended in the milk. This can make digestion by people tricky as the small molecules enter the bloodstream directly as undigested fat. This is why some people refer to being ‘lactose intolerant’.
The Effect on Cheese Making
You are told at cheese making school that it is not a good idea to make cheese out of homogenised milk. I was asked why the other day.
Well…..casein is the main protein found in milk. Casein is usually found in long strings, referred to as micelles.
The homogenisation process (as above) splits up these casein micelles and makes a very soft set on rennetting which tends to break up on cutting.
And that is why you are not supposed to be able to make cheese from milk that has been homogenised.