Sauerkraut

Sauerkraut is made from finely shredded raw white cabbage that has undergone fermentation by various lactic acid bacteria. The sour taste and long storage life come from the lactic acid produced as these bacteria break down the sugars in the cabbage leaves.

The English term comes from the German *Sauerkraut*, meaning "sour cabbage," but the dish itself did not originate in Germany. Roman writers like Cato and Columella described preserving cabbage and turnips with salt, and Pliny the Elder, in the first century AD, is credited with the first written account of making sauerkraut—what the Romans called "salt cabbage"—stored in earthen vessels. A popular legend claims that the Golden Horde’s trade networks introduced sauerkraut to Europe, but there is no evidence for this, nor for an East Asian origin. Instead, evidence shows sauerkraut production in Europe dating back to the early Western Roman Empire. Before refrigeration, freezing, and cheap transport from warmer regions were common in Northern, Central, and Eastern Europe, sauerkraut provided essential nutrients like vitamin C during winter. Captain James Cook carried it on his voyages to prevent scurvy.

Fermented cabbage, known as *suan cai*, may have been made in China during the building of the Great Wall, but the Romans are the more likely source of modern European sauerkraut. It became popular in Central and Eastern European cuisines, including the Netherlands (where it is called *zuurkool*) and France (*choucroute*). According to Mack and Surina, Slavic peoples likely developed fermented cabbage independently. Many Slavic and other languages have names with similar meanings to the German word, such as *kiseli kupus* in Serbo-Croatian, *kysané zelí* in Czech, and *kvašenaja kapusta* in Russian. The word *Kraut*, derived from this food, became a derogatory term for Germans. During World War I, American sauerkraut makers relabeled it as "liberty cabbage" to avoid public rejection of a German-sounding name.

Production involves lactic acid fermentation, similar to traditional pickled cucumbers or kimchi. The cabbage is finely shredded, layered with salt, and left to ferment. Fully cured sauerkraut can be stored for several months in an airtight container at 15°C (60°F) or below, allowing it to last through winter and early spring without refrigeration or pasteurization, though these treatments extend its shelf life. Naturally occurring airborne lactobacilli on the raw cabbage leaves drive the fermentation. Yeasts are also present and can cause soft, poor-flavored sauerkraut if the temperature is too high. The process has three phases, sometimes called population dynamics. First, anaerobic bacteria like *Klebsiella* and *Enterobacter* begin fermentation, creating an acidic environment. Second, as acidity rises, *Leuconostoc mesenteroides* and other *Leuconostoc* species take over. Third, *Lactobacillus* species, including *L. brevis* and *L. plantarum*, ferment remaining sugars, further lowering the pH. Properly cured sauerkraut is acidic enough to prevent *Clostridium botulinum* growth, which causes botulism. A 2004 genomic study revealed greater diversity of lactic acid bacteria than previously thought, with *Weissella* dominating the initial heterofermentative stage up to day 7, and *Lactobacillus brevis* and *Pediococcus pentosaceus* being less abundant in the first 14 days than earlier studies indicated. The Dutch sauerkraut industry found that mixing a new batch with an old one—called "backslopping" or "inoculum enrichment"—produced an extremely sour product, as it bypasses the first two phases of population dynamics due to the early dominance of *L. plantarum*.

Regional varieties vary. In Armenian, Belarusian, Estonian, Latvian, Lithuanian, Czech, Slovak, Polish, Russian, and Ukrainian cuisines, chopped cabbage is often pickled with shredded carrots. Other possible additions include caraway seeds, whole or quartered apples for flavor, or cranberries, whose benzoic acid acts as a preservative. Bell peppers and beets are also sometimes added.