Cheese is a way of keeping milk, and the details are geography

Milk spoils within a day without refrigeration. It is also, for a pastoral household, the most abundant food available for part of the year and unavailable for the rest.

Cheese is the solution: concentrate the fat and protein, remove most of the water, add salt, and let controlled microbial activity do the rest. The result keeps for months or years.

The basic process

Milk is coagulated, separating solid curd from liquid whey. Coagulation is achieved with acid — from souring or from an added culture — or with rennet, an enzyme traditionally obtained from the stomach lining of a young ruminant, or with plant coagulants such as thistle flowers, used in several Mediterranean traditions.

The curd is then cut, drained, sometimes cooked, salted, pressed to varying degrees, and aged.

Each of those steps has a range of options, and the combination produces everything from fresh soft cheese to a hard wheel that will survive a decade.

Why mountain cheeses are large and hard

The most instructive example of how circumstance produces form.

Alpine dairying involved taking herds to high pastures for the summer, where milk was abundant and there was no way to move it fresh. So the milk was made into cheese on the mountain, and the cheese had to survive months and then be carried down.

That produced large wheels — better ratio of volume to surface, less waste, easier to transport a few large objects than many small ones. It produced hard, cooked, pressed cheeses with low moisture, because those keep. And it produced cheeses made from the milk of many animals at once, since a large wheel needs a large quantity of milk, which in turn required cooperative arrangements between households.

Those cooperative dairy institutions are a substantial part of alpine social history, and several of them survive as functioning organisations.

Why some traditions produce small fresh cheeses

Where the dairy was close to the household and the cheese was eaten within days, there was no reason to make it keep. Fresh cheeses across the Mediterranean, the Middle East and South Asia are made quickly, often with acid rather than rennet, and consumed immediately.

Brined cheeses — stored in salt water rather than aged in air — are common in hot climates, where a rind-aged cheese would be difficult to protect. The brine does the preserving and produces a distinctive salty, crumbly result.

The animal matters

Cow milk is abundant and mild, and it dominates where pasture is good.

Sheep milk is much higher in fat and solids, so it yields more cheese per litre, and it produces a richer, more assertive result. Sheep suit poorer, drier and steeper ground, which is why sheep cheese traditions concentrate in such regions.

Goat milk suits marginal terrain and browse rather than grass, and it produces the characteristic tangy flavour that comes from particular fatty acids.

Buffalo, yak, camel, mare and reindeer milk are all used in various traditions, each with different composition and each producing something that cannot be replicated with another animal's milk.

Seasonality matters too. Milk composition changes across lactation and with what the animals are eating, which is why some traditional cheeses are made only at certain times of year and taste noticeably different between spring and autumn production.

What lives in a cheese

Aged cheese is a microbial ecosystem. Lactic acid bacteria acidify the curd. Various moulds, yeasts and bacteria colonise the rind and the interior, each contributing to breakdown of fats and proteins and therefore to flavour.

Traditional cheesemaking relied on organisms already present — in the raw milk, on the equipment, in the ageing cellar, on the wooden shelves. Cellars and boards develop resident populations over decades, and this is a genuine reason that a cheese made in one place differs from the same recipe made elsewhere.

Industrial production uses defined starter cultures for consistency, which is why industrial versions of traditional cheeses are recognisable and different.

The raw milk argument

Raw milk cheese carries a more complex microbial population and, in the view of most people who care about this, more flavour complexity. It also carries food safety risk, which is why regulations vary considerably between countries.

Ageing reduces risk substantially — the acidity, salt and reduced moisture of a long-aged cheese are hostile to pathogens — which is why many jurisdictions permit raw milk cheese above a certain age while restricting fresh raw milk products.

The argument is genuinely a trade-off rather than a case of one side being wrong, and reasonable regulators have landed in different places.

The pressure on traditional production

Small-scale traditional cheesemaking has been squeezed by the same forces as every hand craft: cost, regulation designed around industrial-scale operations, and the difficulty of finding anyone to take on the work.

Protected designation schemes in several countries have helped, by defining what a name means and preventing industrial imitations from using it. They also fix a definition in place, which can freeze a tradition and exclude producers who do things slightly differently.

What has genuinely sustained several traditions is a market willing to pay a large premium for a specific thing — which is a fragile basis, dependent on the continued existence of buyers who know the difference.