Should ketchup be kept in the fridge or the cupboard?

This argument is rarely shouted. It is conducted by opening somebody else's cupboard, finding a bottle of ketchup at room temperature, and saying nothing in a very loud way.

It is also one of the few disputes here with an answer partly written on the packaging, which does not stop anyone. The Court's task is to separate what the label instructs from what the household is actually risking.

The manufacturer's instruction is the most straightforward piece of evidence available. Many labels advise refrigeration after opening, and following the label is not paranoia.

Refrigeration slows the changes that make an old bottle taste dull and look brown. Ketchup is acidic enough to resist spoiling, but resisting spoilage is a lower bar than staying good.

There is a sensory argument too. Cold ketchup against hot chips is a genuine contrast, and warm ketchup on hot food tends towards sweet and flat.

Ketchup's own composition does most of the preserving work: acidity and sugar are why it sat on café tables for generations without incident.

Turnover matters. A bottle that is emptied within weeks has little opportunity to degrade, so the fridge is solving a problem that particular household does not have.

There is a practical complaint as well. Chilled ketchup pours reluctantly and can arrive in one uninvited lump, and it also blunts the flavour of hot food it is supposed to lift.

Check your own bottle. Storage advice varies between brands and recipes, and reduced-sugar or reduced-salt versions are the ones most likely to insist on the fridge.

Restaurant and café practice is not a good guide for a home kitchen. Table bottles are refilled and emptied constantly, which is not how most cupboards work.

The real risk in a cupboard is quality rather than safety: the sauce darkens and tastes tired long before it becomes a hazard. That is why this argument produces so much confidence and so little illness.

Does ketchup actually go off in the cupboard?

It is acidic and sugary enough to resist spoiling for a long time, but it loses colour and flavour faster at room temperature. The usual outcome is a dull, darker sauce rather than an unsafe one.

Why do restaurants leave ketchup on the table?

Because table bottles are used constantly and replaced or refilled quickly, so there is no time for quality to drift. Home bottles often sit far longer.

Does the label always say refrigerate after opening?

No, it varies by brand and recipe. Reduced-sugar and reduced-salt versions are the most likely to require refrigeration, because sugar and salt do part of the preserving.

What about brown sauce and mayonnaise?

Follow each label. Mayonnaise is the strictest of the three because it is egg-based; brown sauce behaves much like ketchup, and both are best judged by their own packaging.