Is milk ultra-processed?

Plain milk is group 1. Whole, semi-skimmed and skimmed are all group 1: skimming removes fat, and removal does not move a food.

Pasteurisation is a heat treatment and adds nothing. Homogenisation breaks the fat globules into smaller pieces so the cream does not separate, which is mechanical and also adds nothing. UHT milk is group 1 for the same reason.

The one to watch

Plain milk is group 1 and plain yoghurt is group 3, because fermenting is a process applied to a food where pasteurising is not. That pair is the single most confusing boundary in the dairy aisle, and it is the one the app's own classifier got wrong on a real receipt before it was corrected.

• Plain milk, any fat content, fresh or UHT: group 1.
• Lactose-free milk: group 1. An enzyme has broken the lactose down, which is a change rather than an addition.
• Flavoured milk and milkshakes: group 4, from sugars, stabilisers and flavourings.
• Condensed and evaporated milk: group 3.
• Plant milks are a different question entirely, covered in oat milk.

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.