Introduction

Lactic acid is a bitter-tasting acid that forms when certain bacteria combine with lactose or milk sugar.  Lactic acid occurs naturally in the souring of milk.

Lactic Acid in Foods

Lactic acid is primarily found in these sour milk products: koumiss, leban, yogurt, kefir, cheese and some cottage cheeses.

Lactic acid is used in the preservation of some foods, to impart a tart flavor, and in the production of acid-fermented foods such as pickles and Sauerkraut.  The casein found in fermented milk is coagulated (curdled) by lactic acid.

Lactic acid is widely used for inhibiting pathogenic bacteria like E.coli, Salmonella, Campylobacter and Listeria on animal carcasses like beef, pork and poultry during the slaughtering process.

Lactic Acid in Processed Foods

Lactic acid may also be found in various processed foods, usually either as a pH adjusting ingredient, or as a preservative (either as antioxidant or for control of pathogenic micro-organisms). It may also be used as a fermentation booster in rye and sourdough breads.

Lactic Acid in the Body

Lactic acid is a by-product of anaerobic glycolysis and anaerobic metabolism.  Although used as a fuel by the heart, excessive lactic acid slows down contractions of the skeletal muscles, preventing you from walking fast.