Self-brining Ferments: Sauerkraut

Introduction

Made with just two ingredients – cabbage and salt – and using the cabbage’s own water to make brine, sauerkraut has a simplicity that means that it is the perfect place to start looking at vegetable fermentation.

History of Sauerkraut

Spoonful of sauerkraut over a jar, beer mug in background

Despite Germany’s reputation as the home of sauerkraut, it actually all began in China. During the construction of the Great Wall in the seventh century bc, the workers used to live on a diet of cabbage and rice. In the summertime, the cabbage was fresh, but during the colder months they were sustained by supplies that had been preserved and fermented in rice wine. Fresh cabbage is a good source of vitamin C, but the nutritional content is much enhanced in sauerkraut.

Brought from China to Europe by the Tartars, at some point sauerkraut began to be cured with salt instead of rice wine, giving rise to what is known today as sauerkraut, which translates from German simply as ‘sour cabbage’. It has been a staple in the Eastern and Central European diet since the 1600s.

In the eighteenth century, sauerkraut played an important part in British naval history. In 1740, Commodore George Anson set off to the Pacific on a mission to disrupt Spanish influence in the region, with a fleet of eight ships and 2,000 men. He returned four years later having lost 90% of the crew to illness, notably scurvy. The ship’s chaplain recorded the appalling effects of the illness:

  • Those affected have skin as black as ink, ulcers, difficult respiration, rictus of the limbs, teeth falling out and, perhaps most revolting of all, a strange plethora of gum tissue sprouting out of the mouth, which immediately rotted and lent the victim’s breath an abominable odor.

The terrible losses brought scurvy to public attention. Scottish naval doctor James Lind noticed that those affected by the condition had a very poor diet, and discovered that citrus fruits helped, although he was unaware at the time that vitamin C was the preventive agent. Fermented cabbage was suggested as another solution and, as an experiment, in 1764, Captain Cook set off on a voyage with a large crew and 7,640 pounds of ‘Sour Krott’. He returned at the end of the expedition having lost not one crew member to scurvy.

Sauerkraut may be a staple food in Germany, but that is not where it originated.

Despite this, the British seem to have lost interest in sauerkraut and it did not become an integral part of Britain’s food heritage. It is most definitely prominent in US culture, though, as an essential component of a salt-beef sandwich, or with a hot dog, introduced to the New World by German immigrants arriving there in the eighteenth century. Also learn about curing and smoking.

Germany’s National Dish. E. Moreland

In Germany, per capita consumption of sauerkraut has almost halved over the past 40 years, probably due to the globalization of food markets and the prevalence of convenience foods. A similar picture of the loss of traditional eating patterns emerges all over Europe. Nowadays, much of Germany’s sauerkraut is pasteurized to make it shelf-stable, so it has no probiotic benefit, although it is still effective as a source of fibre. To be fair, it is traditionally commonly served hot as a side dish or in stews, which effectively pasteurizes it anyway.

There are various different types of sauerkraut: although used as a blanket term, the word usually describes the foodstuff made from white cabbage (blaukraut is made from red cabbage and filderkraut from pointed cabbage). Savoy and green cabbages can also be used. Generally, these days, the abbreviation ‘kraut’ is used to describe any ferment with shredded vegetables and cabbage as a base.

Cabbage: The Raw Material

Cabbage, Brassica oleracea, is part of a large group of cruciferous vegetables (so called because their four-leaved flowers resemble a cross), which includes cauliflower, kohlrabi, broccoli, kale, Brussels sprouts, spring greens, Swiss chard and rocket. The word is derived from the French caboche, a colloquial word for ‘head’ or in English, perhaps noodle or noggin? We still use the phrase ‘a head of cabbage’.

There are at least a hundred different cultivars of cabbage to choose from when making sauerkraut. Although you may be limited by what is available to buy, if you have an allotment you could choose to grow one of the heirloom varieties, such as Brunswick or Golden Acre. The cool British climate is perfectly suited to cabbage cultivation, which started in the fourteenth century. The vegetable is in season all year round and takes between 70 and 120 days to reach maturity. All of these types of cabbage have slightly different qualities.

Chinese, hispi, savoy red and white cabbages in all their unsauerkrauted glory.

White or Green Cabbage

The popularity of the very familiar green cabbage has faded recently, to be replaced almost always by white cabbage. Firm, crisp and peppery to the bite, this stalwart of sauerkraut requires three weeks’ fermentation at room temperature.

Pointed or Hispi Cabbage

A type of green cabbage with loosely packed pointed leaves. It has a softer texture and a sweeter taste. It is much quicker to ferment than the basic white or green cabbage, taking five to seven days to reach a good texture and flavour.

Red Cabbage

The colour of red cabbage is due to the presence of the anthocyanin cyaniclin, which can also be used as a pH indicator; this is very helpful when fermenting. Anthocyanins are known to be a choice food for the gut microbiota and to have antioxidant properties. The flesh of the red cabbage is the most durable of all the varieties and takes several weeks to reach a pleasant consistency (although there are ways of speeding this up in mixed ferments).

Savoy Cabbage

Savoy cabbage is delicious fermented. The outer leaves can take weeks to tenderize through fermentation whilst the inner leaves can be soft within a week.

Napa Cabbage

The stalwart of kimchi, this Chinese cabbage is also a popular ingredient in East Asian cooking. It has a completely different, more lettuce-like texture than the other members of the family. When fermented, the stems retain their structure whilst the leaves wilt to almost nothing. Kimchi made from napa cabbage can be ready to eat within three to five days.

Nutritional Content of Sauerkraut

White cabbage comprises about 90% carbohydrates, approximately one-third as dietary fibre and two-thirds as other carbohydrates, including glucose, fructose, sucrose and raffinose. Glucosinolates give brassicas their characteristic flavours and that slightly sulphurous odour, and there are high levels of vitamin C, especially in red cabbage.

During fermentation, bacterial metabolism alters the composition, resulting in sauerkraut with an increased content of minerals, antioxidants including vitamin C, and also vitamins A, some B6, and K2, folate, iron, organic acids, breakdown products of glucosinolates, sulphorophanes, histamine and tyrosine. In fermented red cabbage there are higher levels of flavonoids and anthocyanins. It also contains an enormous population of potentially probiotic microbes. Also check out about salting.

Health Benefits of Sauerkraut

Even today, when there is so much enthusiasm for fermented foods, the health effects of sauerkraut consumption on human subjects have not been extensively studied. However, the probiotic and bioactive phytochemical content is undeniable. Below are some of the positive findings.68

Antioxidant Action

Sauerkraut contains high levels of free radical scavengers that can protect cells from oxidative stress.69 In addition, the high levels of vitamin C can reduce levels of C-reactive protein, which is involved in inflammation and atherosclerosis.70

Anti-Carcinogenic Properties

Glucosinolate breakdown products have been shown to be involved in detoxification pathways for some environmental carcinogens in rat livers and kidneys. In human breast cell lines, sauerkraut juice was involved in the inhibition of oestrogen production, suggesting a potential protective activity against breast cancer.71 A case-control study in Polish migrant women in the USA showed that raw or lightly cooked cabbage, and/ or sauerkraut consumption, at least three times a week during adolescence and adulthood, was linked with a 72% reduction in breast cancer risk. Breast cancer incidence in these communities had tripled within one generation, pointing to diet as a risk factor.72

Anti-Inflammatory Effects

Several bioactive components of sauerkraut are able to inhibit the production of nitric oxide, which is an inflammatory marker produced by activated macrophages, important cells involved in the immune response. Sauerkraut is much more effective than raw cabbage.73

Probiotic Action

It can only be roughly estimated, as it will vary according to culture conditions, but sauerkraut samples have been found to contain in the region of 106–108 cfu/g lactic acid bacteria. That is 1,000,000 to 100,000,000 per gram, and in a 100-gram serving, 10,000,000 to 1,000,000,000. Up to 15 different types of LAB have been detected in sauerkraut samples.

Mechanism of Sauerkraut Fermentation

Chopped iceberg lettuce on a green surface

Complete fermentation of white sauerkraut takes about 20 days. The microbiota is established very quickly when fermentation begins. The microbes present can vary significantly at the start of the process, depending upon what is present on the vegetables, and LAB may represent only about 5% of the starting population. However, they always make it through and dominate in the final product, which is just as well as they are responsible for producing the organic acids, bacterioicins, vitamins, and volatile flavour compounds that characterize sauerkraut.

The first stage in the process is the initial proliferation of Leuconostoc mesenteroides, one of the commonest commensal organisms associated with vegetables. It is able to tolerate the salty conditions and, in the anaerobic environment provided, breaks down the available sugars to produce lactic acid, carbon dioxide and ethanol through heterolactic fermentation. During this time, the number of bacterial species drops rapidly, as production of antimicrobial substances, increased acidity and salt take their toll on undesirable organisms. This alters the environment so that a different organism, Lactobacillus plantarum, is able to thrive, and continues to do so for the main fermentation period. At the end, it facilitates an increase in Lactobacillus brevis, for ‘finishing off’ for the last few days. By the end of the period, LAB account for about 90% of the microbes present.

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