Is mayonnaise ultra-processed?

Full-fat mayonnaise is usually group 3: oil, egg yolk, vinegar, mustard and salt. The egg yolk is doing the emulsifying, and egg yolk is a food rather than an additive.

The light versions go the other way

Take out most of the oil and the emulsion has nothing to hold it together and nothing to give it body. Reduced-fat and light mayonnaise therefore add starches, gums, stabilisers and often sweeteners, which puts them in group 4.

This is the same relationship as reduced-sugar baked beans, low-fat yoghurt and spreads. Removing something means adding something to do its job, and the addition is what moves the classification.

It is worth saying plainly that this does not make full-fat mayonnaise a better choice in any sense NOVA measures. The two differ substantially in fat and energy, and the classification is not weighing either.

Other dressings

• Oil and vinegar, or a vinaigrette of oil, vinegar and mustard: group 2 or 3.
• Salad cream: usually group 4.
• Bottled creamy dressings, ranch and caesar: usually group 4.
• Ketchup is generally group 3, being tomatoes, sugar, vinegar and salt.

Working this out from a receipt is harder than from a packet, because a till prints about twenty characters of product name and no ingredients list. That is the problem Bagged exists to solve, and how a receipt is structured explains why it is the hard part.