Tartaric Acid
What it does
Sour flavour, acidity regulator.
How it's made
From grape processing (winemaking).
Tartaric acid is a naturally sour acid most famously associated with grapes and wine, where it is the main acid present. In food it provides a sharp taste, regulates acidity and works with raising agents in baking. It is one of the few food acids still obtained largely from a natural by-product rather than by synthesis.
The main source is the wine industry. During winemaking, tartaric acid and its potassium salt crystallise out as "argols" or wine lees on the sides of fermentation tanks and barrels. These deposits are collected and treated with calcium to form insoluble calcium tartrate, which is then reacted with sulphuric acid to release purified tartaric acid.
The freed acid is filtered, concentrated and crystallised into a white food-grade powder. Because it comes from grapes, natural tartaric acid has a single specific molecular form; a synthetic route exists but produces a different mixture, so the grape-derived product remains the standard for food use.
Possible reactions
Generally safe; large amounts are laxative.