Tomato sauce

Tomato sauce is tomato reduced for an hour and then kept - and both halves matter: the reduction concentrates the histamine that was there, and a jar or a pan kept in the fridge for days keeps building. A sauce made and eaten the same evening is a different food from the half-jar at the back of the shelf.

Tomato sauce is cooked-down tomato, and cooking concentrates the FODMAP sugars while removing nothing. Half a cup is around the limit for a plain passata; a jarred sauce with onion and garlic in it is a different food and a different answer.

The tomato is not the issue on this axis - tomato brings sugar, not chains. What puts a jarred sauce here is the onion and garlic cooked into it, which is why a plain passata and a ready-made sauce are not the same food. This is a PREPARED food, and that is the difficulty on this axis: the oligosaccharides come from whatever went in - onion, garlic, a legume, an added fibre - not from a single plant that could be looked up. The level follows work on fructooligosaccharides in prepared and preserved foods for that reason. The survey behind this ranks by PLANT FAMILY rather than by food: the Compositae highest in total fructooligosaccharide, then the Allium species. A prepared food takes its place from whichever of those went into it - onion and garlic are Allium, artichoke and chicory are Compositae - and the survey names no prepared food itself.

Reducing tomatoes into sauce boils off water and concentrates the salicylate, so a portion of sauce carries more than the fresh tomatoes it took to make it.

Tomato sauce is tomato, and tomato has no gluten - but a jarred pasta sauce is often thickened with wheat flour or carries a 'may contain' line from a factory that also makes filled pasta. A plain passata with one ingredient does not.

Tomato sauce carries the tomato's own small fructose load, and many commercial jars add sugar on top to balance the acidity. Passata without added sugar is lower.

Tomato sauce carries the tomato's own small sucrose share, and many jars add sugar to balance the acidity - which is why an own-brand passata and a premium jarred sauce can differ several-fold.

Tomato sauce is cooked tomato, where heat ends any bacterial activity. Tyramine needs three things - protein, bacteria and time - and a cooked or dried product has had the second removed and the third stopped.

Tomato sauce is cooked tomato, usually in a can. Acid plus heat plus metal is the combination that transfers most, and this is the food where it happens most often.

Tomato sauce concentrates tomato, and the tomato's oxalate concentrates with it. Tomato sauce is eaten as a plate-sized portion rather than a spoonful, which is what makes the concentration count here.