Lactic Acid
What it does
Acidity regulator, preservative.
How it's made
Made by fermenting sugars.
Lactic acid is the mild, slightly tangy acid found in soured milk, yoghurt and many fermented foods. In manufacturing it is used to adjust acidity, add a gentle sourness and help preserve foods, and because it is produced naturally by fermentation it is well accepted as a food ingredient.
It is made commercially by fermenting sugars with lactic-acid bacteria (such as Lactobacillus species). Manufacturers feed the bacteria a carbohydrate source — commonly glucose from corn or beet sugar — in large fermenters kept at a controlled temperature, and the microbes convert the sugar into lactic acid. The acidity that builds up is usually neutralised during fermentation to keep the bacteria working, then the acid is released again during purification.
The crude fermentation broth is filtered and purified to food grade, and the acid can be concentrated to the required strength. The food-grade product is typically the naturally-fermented form; a chemically synthesised version exists but yields a mix of two mirror-image forms, whereas fermentation gives mainly the form the body handles most readily.
Possible reactions
Generally safe; naturally in fermented foods.