What it does
Vinegar is buffered so that it inhibits microorganisms without acidifying the product to the point where the taste changes. Fermentates go further: a substrate is fermented and the whole metabolite mixture is used, which brings organic acids and other inhibitory compounds together. The hurdle is chemical, unlike a bioprotective culture, but the declaration is a food ingredient rather than a preservative.
Where it works
Cooked meat, chilled prepared foods, sauces and bakery where the brief demands a shorter label and the limit is microbiological. It is the most common single answer to a clean label preservation requirement.
Where it does not
It is less potent per unit than the preservative it replaces, so the level needed is higher and the flavour contribution becomes real. In a delicate product that vinegar note is detectable, and masking it is a separate problem. It also does nothing about oxidation.
What it interacts with
pH, which decides how much of the acid is in the active undissociated form. Salt, which works with it. Other hurdles, with which it is designed to be combined.
