Interesting facts about milk and other dairy products

What makes milk boil over?
Milk is the only liquid that forms a skin and boils over when it is cooked. Milk proteins are responsible for this anomaly: some curdle when heated to a boiling point, and form a thin skin on the surface of the liquid. The water accumulates below this skin, which then rises, and the milk overflows.
Tip: Stir milk as it begins to boil. The milk proteins will trap small air bubbles, and will create foam. This helps prevent the milk from boiling over. 

Why do some cheeses have holes? 
During the ripening process, certain bacteria cultures transform lactose into lactic acid. Carbon dioxide is a by-product of this process, but cannot escape through the curd and rind. The gas collects, and creates cavities of various sizes – which become the familiar holes we find in many cheeses. 

Can one freeze dairy products?
Butter can be frozen without hesitation: neither the taste nor the texture is adversely affected. Portions of cream can likewise be frozen; after defrosting, it is best used in cooking. Similarly, you can freeze fresh milk and fresh cheese without sacrificing much quality. Pieces of table cheese can be frozen, it’s true – but it has a tendency to become dry and lose flavour. It is thus recommended that cheese be bought fresh and consumed relatively quickly. Yoghurt, however, should not be deep-frozen.

What is pasteurisation? Does this process affect the quality of milk?
Pasteurisation is a process developed by Louis Pasteur in which milk is heated to a temperature of at least 72º C for a short period of time. This destroys all harmful pathogens that may exist in the milk, but does not adversely affect its nutritional value. 

What is meant by “homogenisation”?
Homogenisation means that the milk is pushed through very small nozzles at a pressure of 150 Bar. The small globules of milk fat are broken down through this process, and distributed uniformly. Homogenisation renders it nearly impossible for the milk fat to separate from the liquid, and the milk becomes more digestible as well.

What is the difference between sweet cream and cultured butter?
Sweet cream butter is made directly from fresh cream. Cultured butter, on the other hand, is made from cream that has undergone an acidification or souring process. In olden days, it was not possible to prevent cream from souring naturally on mountain pastures and alpine farms, due to the lack of proper refrigeration. Today we love the unique and fresh taste of cultured butter so dairies have developed processes in which selected lactic acid bacteria are added to cream to sour it. 

What are the differences – other than taste – between cow’s milk and goat’s milk?
One important difference is the structure of the milk fats. In goat’s milk, they are held together by a fairly weak bond and can be broken down easily. This makes goat’s milk easier to digest. Goat’s milk is also a fabulous source of amino acids, vitamins and minerals.
For those who suffer from lactose intolerance (an allergy to milk), goat’s milk and its derivatives offer a viable alternative.