Scaling a home recipe to a hundred portions

A recipe that feeds four does not become a recipe that feeds a hundred by multiplying everything by twenty-five. Some things scale linearly, several do not, and one of the things that does not is a food safety problem rather than a flavour one.

What scales cleanly

Bulk ingredients, mostly. Rice, meat, vegetables, coconut milk, stock. If it is a major component by weight, multiply it and you will be close.

Salt scales roughly linearly too, though you should still taste rather than trust the arithmetic, because everything around it has changed.

What does not

Aromatics and chilli

Strong aromatics are usually less than linear. Twenty-five times the garlic, ginger and dried chilli tends to overshoot, sometimes badly. The practical approach is to scale these to around seventy or eighty percent of the arithmetic, then taste and correct upwards, which you can do. You cannot correct downwards.

Evaporation

This one surprises people. A small pot has a lot of surface relative to its volume; a large pot has proportionally much less. The same simmer that reduces a home-sized curry nicely will leave a hundred-portion batch watery, because far less water is leaving.

You will need longer reduction, a wider vessel, or less liquid at the start. Plan for it rather than discovering it an hour before service.

Cooking time

Not linear in either direction. A large mass takes considerably longer to come up to temperature and considerably longer to cool. Meanwhile the individual pieces of chicken in it cook at the same rate they always did, which means the outside of the batch can overcook while the middle is still climbing.

Browning

The limit that catches every home cook going commercial. You cannot brown ten kilograms of anything at once, for the same reason you cannot get wok hei in an overcrowded pan: the moisture cannot leave fast enough, so it steams.

Browning has to be done in batches even when the rest of the cooking does not. Yes, it takes longer. It is also where most of the flavour lives, and skipping it is the most common reason a scaled-up dish tastes flat compared with the original.

Rempah

A large batch of rempah needs disproportionately more frying, not less. More paste, more water to drive off, less surface area to do it through. If fifteen minutes worked at home, budget forty or more, and wait for the oil to separate rather than watching the clock.

Weigh everything, and write it down

Home cooking runs on handfuls and instinct, and that works because the same person cooks it every time.

At volume it stops working, because consistency becomes the product. A customer who liked it last week is buying the expectation that this week is the same. Instinct cannot deliver that across different staff, different days and different batch sizes.

So: scales, not cups. Grams, not handfuls. A written recipe with quantities, sequence, timings and the visual cues that tell someone it is ready. That document is the thing that lets you take a day off.

It is also the foundation of every certification you will eventually want. A documented, repeatable process is most of what MeSTI, GMP and HACCP are asking for.

Scale in stages

Do not go from four portions to a hundred in one jump. Go to twenty, cook it properly, taste it, write down what you changed. Then to fifty. Then to a hundred.

Each step reveals a different problem: twenty finds the seasoning, fifty finds the equipment limits, a hundred finds the timing and the cooling. Discovering all three at once, with an order to deliver, is how people end up serving something they are not happy with.

The equipment ceiling

At some point the answer stops being technique and becomes hardware. A domestic hob cannot heat a fifty-litre pot properly. A home fridge cannot chill twenty kilograms of hot curry safely. A single oven cannot bake for a hundred covers.

Recognising that ceiling early is useful, because the alternatives are real: rent a commissary kitchen by the session, or produce through someone with the equipment and certification already in place. Both are cheaper than buying equipment for a volume you are not yet reliably selling.