Sauerkraut

Sauerkraut is a traditional food made from finely shredded white cabbage preserved by lactic acid fermentation. This fermentation happens naturally: beneficial lactic acid bacteria convert the sugars in the cabbage into lactic acid. As a result, the cabbage becomes sour, keeps longer and acquires its typical taste. For children from about 12 years old this can be remembered like this: From simple cabbage, friendly bacteria create a “super cabbage” that lasts much longer and tastes pleasantly sour.

Origin and distribution
Sauerkraut is known in many countries. It is particularly famous in Germany, Austria, Poland, the Czech Republic, Switzerland and parts of France. In Korea there is a very related idea, kimchi, which is spicier. In Europe sauerkraut has been produced for centuries because it replaced fresh vegetables in winter and provided important vitamins. On ships it served for a long time as protection against scurvy because it contains vitamin C. Today sauerkraut can be found worldwide in supermarkets, organic shops, delicatessens and at weekly markets.

Availability throughout the year
Basically sauerkraut is available year-round. Production does depend on the cabbage harvest, but because sauerkraut is preserved by fermentation, it can be stored and sold for many months.

Sauerkraut is a fermented food based on finely shredded white cabbage leaves (Brassica oleracea var. capitata), whose production is carried out by lactic acid fermentation. Characteristic are a low pH, a high content of organic acids and a complex microflora of lactic acid bacteria (LAB). These parameters give the product its typical acidity, shelf life and nutritional peculiarities.

Raw material and processing
The starting material is fresh, firm cabbage heads with a high dry matter content and a sugar content typically of 3–6 percent, mainly as glucose and fructose. The cabbage is cleaned, quartered, cored and mechanically cut into fine strips (usually 0.8–2.0 mm). By salting (typically 1.5–2.5 percent NaCl based on the cabbage mass) cell sap is osmotically released, creating an anaerobic environment in its own juice. Compacting the shredded cabbage in fermentation vessels minimizes residual oxygen and favors the desired microorganisms.

Microbiology and fermentation dynamics
Fermentation is initiated spontaneously by epiphytic lactic acid bacteria or controlled by starter cultures. In early phases facultatively anaerobic species such as Leuconostoc mesenteroides dominate, which at moderate temperatures (18–22 °C) produce CO2 and lactic acid and rapidly lower the pH. They are followed by acidophilic species, typically Lactiplantibacillus plantarum (syn. Lactobacillus plantarum) and Limosilactobacillus fermentum, which predominantly produce lactic acid homofermentatively. Optionally heterofermentative pathways appear, generating besides lactic acid also acetic acid, ethanol and CO2. An end pH of 3.2–3.8 is common; titratable acidity (as lactic acid) often ranges between 0.7 and 1.8 percent. Successful fermentation suppresses undesirable microflora, microbiologically stabilizes the product and extends shelf life.