Sauerkraut - Producing Sauerkraut

Producing Sauerkraut

Sauerkraut is made by a process of pickling called lacto-fermentation that is analogous to how traditional (not heat-treated) pickled cucumbers and kimchi are made. Fully cured sauerkraut keeps for several months in an airtight container stored at or below 15 °C (60 °F). Neither refrigeration nor pasteurization is required, although these treatments prolong storage life. German sauerkraut is often flavoured with juniper berries.

Fermentation by lactobacilli is introduced naturally, as these air-borne bacteria culture on raw cabbage leaves where they grow. Yeasts also are present, and may yield soft sauerkraut of poor flavor when the fermentation temperature is too high. The fermentation process has three phases, these phases are sometimes referred to as population dynamics. In the first phase, anaerobic bacteria such as Klebsiella and Enterobacter lead the fermentation, and begin producing an acidic environment that favours later bacteria. The second phase starts as the acid levels become too high for many bacteria, and Leuconostoc mesenteroides and other Leuconostoc spp. take dominance. In the third phase, various Lactobacillus species, including L. brevis and L. plantarum, ferment any remaining sugars, further lowering the pH. Properly cured sauerkraut is sufficiently acidic to prevent a favorable environment for the growth of Clostridium botulinum, the toxins of which cause botulism.

A 2004 genomic study found an unexpectedly large diversity of lactic acid bacteria in sauerkraut, and that previous studies had oversimplified this diversity. Weissella was found to be a major organism in the initial, heterofermentative stage, up to day 7. It was also found that Lactobacillus brevis and Pediococcus pentosaceus had smaller population numbers in the first 14 days than previous studies had reported.

The Netherlands sauerkraut industry found that inoculating a new batch of sauerkraut with an old batch resulted in an excessively sour product. This sourdough process is known as "backslopping" or "inoculum enrichment," and when used in sauerkraut, first stage and second stage population dynamics are bypassed, which are important to developing flavor. This is due primarily to the greater initial activity of species L. plantarum.