Is margarine ultra-processed? And butter?

These two sit further apart under NOVA than almost any other pair on the same shelf, and the reason shows the logic of the classification more clearly than anything else in a supermarket.

Butter is group 2

Butter is churned cream, and salted butter is churned cream with salt. That makes it a processed culinary ingredient: something extracted from a group 1 food by a physical process, used to cook with rather than eaten alone.

Most spreads are group 4

A tub of spread is an emulsion built to behave like butter at fridge temperature while containing less fat. Doing that needs emulsifiers, usually stabilisers, and generally colours and flavourings so it looks and tastes like the thing it is standing in for. That is group 4.

• Butter, salted or unsalted: group 2.
• Ghee and clarified butter: group 2.
• Pure olive or rapeseed oil: group 2.
• Spreads, including olive oil spreads and anything sold in a tub: usually group 4.
• Anything with added plant sterols or added vitamins is group 4 on that alone.

This is one of the cleanest illustrations of NOVA not being a nutrition judgement, and it is worth being explicit about. Butter and a spread differ substantially on fat composition, and the classification is not weighing that at all. It is describing how each one was made. Anybody reading a group 2 as an endorsement has read the wrong thing into it.

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.