Is fruit juice ultra-processed?

Pure fruit juice is group 1. Pressing a fruit removes things and adds nothing, and reconstituting from concentrate is removing water and putting it back, which also adds nothing.

This is one of the clearest cases of NOVA describing manufacturing rather than nutrition, and it is worth sitting with. A glass of orange juice is group 1 by the same test that makes an orange group 1. The classification is not making a claim about the two being equivalent in any other respect, because it does not make claims of that kind at all.

Where it stops being juice

• Juice drink, which is legally a different thing from juice: usually group 4, with sweeteners, flavourings and colours.
• Squash and cordial: group 4, for the same reasons.
• Smoothies of blended fruit and juice with nothing added: group 1. With added flavourings, sweeteners or vitamins: group 4.
• Anything fortified with added vitamins is group 4 on that alone, exactly as with breakfast cereal.

The label word is the reliable signal. Juice, juice from concentrate and juice drink are legally distinct terms in the UK, and only the third one implies additions.

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.