The label on the front of a packet is marketing. The label on the back is the recipe, and it is written in order of weight, which makes it far more useful than any claim printed above it. You can learn most of what matters in the time it takes to turn the box around.

Test one: count the list

Length is a rough proxy for processing. A jar of good passata has two or three lines. A jar of pasta sauce engineered to sit on a shelf for eighteen months has fifteen. Neither number is a moral judgement — but if a food you could make at home from five things arrives with twenty, the extra fifteen are doing a job that time, heat or refrigeration used to do.

Test two: read the first three

Because the list is ordered by weight, the first three ingredients are essentially the product. If sugar, refined oil or water leads the list of something you thought was a savoury food, you have learned what you are actually buying. A wholemeal loaf whose second ingredient is sugar is a cake with ambitions.

If the first three ingredients would surprise the person the food is named after, put it back.

Test three: look for the industrial-only words

You are not looking for chemicals — salt is a chemical. You are looking for ingredients that exist only inside a factory, because they are the clearest signal that the food was engineered rather than cooked:

  • Emulsifiers and stabilisers (mono- and diglycerides, polysorbates, carrageenan)
  • Modified starches
  • Protein isolates and hydrolysed protein
  • Glucose-fructose syrup and maltodextrin
  • "Flavourings" — a legal term that can stand in for an entire missing ingredient

None of these will hurt you this afternoon. They are simply a reliable marker of a category of food that is easy to overeat and hard to cook from. When one shows up in something you eat every day — bread, yoghurt, sauce, stock — that item goes on the short list of things worth making yourself.

What this is not

This is not a purity project. Tinned tomatoes, dried pasta, frozen peas and good vinegar are all processed, and all of them are in nearly everything I cook. The question is never whether a food has been processed. It is whether the processing replaced cooking, or made it possible.