Though never used in its pure form as a flavouring in the kitchen, the taste of lactic acid is well known to us all in sour milk. In 1857, Pasteur discovered that bacteria were responsible for the souring of milk, and since then an enormous number of bacteria capable of doing this have been isolated. Such bacteria are very common and may be reckoned to be present on almost all unsterilized articles in the kitchen.
Lactic acid bacteria ferment simple sugars in the same way as yeasts, but because one enzyme (carboxylase) present in yeast, is absent in lactic acid bacteria, the end product is not alcohol but lactic acid. Some organisms will convert ninety-five per cent of the fermentable sugars to lactic acid: others form a mixture of lactic and acetic acid or similar volatile organic acids responsible for flavouring.
Lactic Acid Benefits, Uses and Recipes Photo Gallery
Sour milk products are of such importance that they have a separate section. Lactic acid fermentation also produces sauerkraut and sour cucumber (dill pickle) and develops flavour in other pickles. I have, for instance, a recipe from North India for spicy fermented turnip pickle.
Sauerkraut (German sauer: acid, Kraut: cabbage) is made by lactic fermentation of finely shredded cabbage with from two to three per cent of salt. The finely shredded cabbage is packed into tubs in layers sprinkled with the salt and kept down by weights under the surface of the liquid, extracted by osmosis from the cabbage. This provides ideal conditions for the growth of a sequence of bacteria producing lactic acid. The one and a half to two per cent of acid formed acts then as a preservative. In other words, it makes a pickle. In making sour cucumber, the bacteria act in a similar way. The making of such products at home is not as difficult as it sounds, for these are everyday peasant operations in some countries.
In sauerkraut, sugars have been largely if not completely used up, so we have an ideal vegetable for slimming. Lactic acid also has a good effect on the digestion and rapidly kills or immobilizes organisms that might cause tummy upsets or disease.