Apple cider vinegar

Apple cider vinegar is a double fermentation - sugar to alcohol, then alcohol to acid - and amines accumulate through both. Unfiltered vinegar with the mother carries more than the clear filtered kind, because the culture is still there. Ordóñez put apple vinegar among the LOWEST of the five surveyed for total biogenic amines, which is the measured backing for the level here.

Cider vinegar is apple that has been eaten twice: yeast turns the sugars into alcohol, then bacteria turn the alcohol into acetic acid. The fructose and sorbitol that put an apple at the top of this axis are consumed on the way and do not come back. A tablespoon in a dressing is a tablespoon of acid and water.

Sorbitol is the polyol that makes apples and stone fruit difficult, and yeast metabolises it along with everything else fermentable. What survives a double fermentation is acetic acid, water and traces of aroma. The unfiltered kind with the 'mother' carries a little more of the second than the clear kind, and none of the first.

The apple is the textbook excess-fructose fruit - more fructose than glucose, which is what this axis is actually about - and its vinegar carries neither. Fermentation is not a reduction here but a conversion: the sugar became something else entirely, and what is left has no sweetness to it at all. Taste is a fair guide for once.