Cooking regime

Cooking without heat

Food can be transformed without heat at all. Acid denatures protein, salt draws out water, enzymes cut proteins apart, and microorganisms rebuild flavour from the inside. All of these change food profoundly — and none of them is cooking.

The five mechanisms

Acid

Denatures protein much as heat does. Ceviche, escabeche, gravlax with citrus, tiradito. The fish turns opaque and firm without heat.

Salt

Draws water out by osmosis and changes protein structure. Curing, gravlax, salt cod, preserved lemons, salted egg yolks.

Enzymes

Proteases cut protein chains. Fruit enzymes in marinades, and the ageing of meat and cheese.

Microorganisms

Bacteria and yeasts producing acid, alcohol and hundreds of flavour compounds. Kraut, kimchi, yoghurt, cheese, miso, bread.

Mechanical action

Pounding, whipping, kneading and emulsifying all change structure without heat. Mayonnaise and gluten development are both this.

Time and drying

Air-drying, ageing and maturing, which are all several of the above acting slowly at once.

What acid does, and what it does not

The comparison between ceviche and cooking is genuinely apt at the level of protein structure: acid unfolds protein chains and lets them link together, which is why the flesh turns from translucent to opaque and firms up exactly as it would in a pan.

But the resemblance stops at the surface. Acid does not do the other things heat does. It does not make food safe in the way cooking does, it does not convert collagen to gelatine, and it does not produce any of the browning compounds that give cooked food its depth.

Whether a raw or acid-treated preparation is safe to eat depends on the fish or meat, its handling, its freezing history and its provenance. That is a food-safety question and FoodHQ does not answer it. Whether a food is safely cooked is a matter for a food safety authority rather than for a description of how the heat arrives. In the UK the Food Standards Agency sets that guidance and it is the one to follow.

What belongs to this regime

• Ceviche, tiradito and escabeche — acid on fish.
• Gravlax and other salt cures — salt and sugar drawing out water over days.
• Fermented vegetables — kraut, kimchi, pickles in brine, where bacteria do the work.
• Cultured dairy — yoghurt, kefir, buttermilk, crème fraîche, cheese.
• Miso, soy sauce, fish sauce and vinegar, all long fermentations.
• Emulsions — mayonnaise, aioli, vinaigrette, all made cold and mechanically.
• Set desserts — anything using gelatine, agar or pectin, which are structural rather than thermal transformations.
• Aged and dried things — hung meat, air-dried ham, matured cheese, dried fruit.

Working in this regime

1. Understand which mechanism you are relying on, because the timings and the controls differ completely.
2. Take safety guidance from a food safety authority rather than from a recipe, particularly for anything raw, cured, cold-smoked or fermented for keeping.
3. Use time as the main variable. Almost everything here is controlled by how long rather than how hot.
4. Control temperature anyway. Cold slows every one of these processes and warmth speeds them, which is a lever rather than an absence of one.
5. Taste at intervals where you can. A ferment, a cure and a marinade all pass through the point you wanted and keep going.
6. Keep salt and acid quantities from a source you trust rather than adjusting them by taste, because in preserving they are structural.
7. Expect the results to be different in kind from cooked food rather than a substitute for it.

Common questions