Cheese is a very early form of food processing to improve storage. Milk is a valuable food because it is an excellent source of protein, energy from both fat and sugars and nutrients like calcium and phosphorus, but it has to be used right away or it spoils. The very first cheeses and yoghurts were almost certainly naturally spoiled milk that people noticed kept longer and could still be used.
Yoghurt is just milk fermented by bacteria, cheese is first acidified with bacteria and then mixed with rennet. The bacteria convert the milk sugar lactose into lactic acid, and which bacteria and how much is converted influences the final taste of the cheese. Some modern cheeses actually use vinegar or lemon juice to make a very acid mix.
Rennet is an enzyme mix from a young mammal’s stomach, they use it to help digest the proteins in the milk they drink, which is pretty much what we do in cheese. Rennet separates milk into solid curds and liquid whey, just like Miss Muffet ate. The curds are used to make the cheese.
It would have easily happened by accident, because animal stomachs have been used for storage for thousands of years – they make convenient water-proof bags with just two openings. So the first cheese was probably just soured and separated milk that had been stored in a calf’s stomach and people needed the food enough not to be fussy about it.
There are other sources of rennet today, including enzyme mixes from different plants and micro-organisms, but many are still produced from stomachs from the meat industry. Vegetarian cheeses use vegetable or engineered rennet.
Adding salt helped cheese keep even longer, because salt stops bacteria by dehydrating them. Before refrigeration salt was an incredibly important means of preserving food, which is why soldiers were partially paid in salt (the origin of ‘salary’). Loose salty cheeses like feta, especially with other herbs added for flavour, are the style of early cheeses.
Once milk and cheese making made it to Europe cooler weather meant they could take longer to age and mature cheeses and didn’t need so much salt to preserve them. This led to the explosion of cheese styles influenced by everything from the cattle feed to the bacteria to the way the curd was worked and compressed.
Cheese today is still one of the world’s most popular foods and is highly nutritious in a diet not overloaded with fats. From a series of lucky accidents we now understand and can control the complex processes to produce all sorts of cheeses. That’s an amazing series of practical experiments stretching back thousands of years.
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