BACTERIA AND SAUERKRAUT FERMENTATION

Sauerkraut Fermentation

Sauerkraut fermentation requires almost no work on the part of the operator. Cabbage contains enough lactic acid bacteria in order to ferment and produce sauerkraut with salt alone. In order to obtain product of the highest quality all those bacteria strains must ferment in a certain sequence. This happens naturally as long as sauerkraut is fermented around 65° F (18° C).

1. Leuconostoc mesenteroides - they are the smallest and start the fermentation first producing around 0.25 to 0.3% lactic acid. They are heterofermenters, this means that they produce different compounds such as lactic acid, acetic acid (vinegar), ethyl alcohol, carbon dioxide (soda gas) and mannitol. The last one is a bitter flavored compound which is metabolized later by Lactobacillus plantarum. All those acids, in combination with alcohol from aromatic esters, contribute to the characteristic flavor of the high quality sauerkraut. If the temperature is higher than 72° F (22° C) they might not grow and that would be detrimental to the flavor of sauerkraut. In about 2 days Leuconostoc mesenteroides will produce 0.3% lactic acid and this increased acidity will restrict its growth. Nevertheless, the enzymes it produced will continue to develop flavor.
2. Lactobacillus plantarum - this strain takes over the production of lactic acid from Leuconostoc mesenteroides and continues fermenting until an acidity level of 1.5 to 2% is achieved. L. plantarum will ferment at temperatures higher than 72° F (22° C) and it can grow at higher acidity levels. It will ferment at lower temperatures as well, albeit at much slower rate. Lactobacillus plantarum is the most popular lactic acid bacteria strain and it ferments sauerkraut, pickles, cheese and even meat. This bacteria is a homofermenter what means that it produces one compound only. It consumes sugar and produces lactic acid which imparts acidic taste to fermented food. At the end of this stage sauerkraut has an acceptable quality and can be served or canned. If there is enough sugar left, the fermentation will continue until all sugar supply is exhausted.
3. Lactobacillus pentoaceticus ( L.brevis) - continue fermenting until an acidity level of 2.5 - 3% is obtained. As there is no more sugar left in the cabbage the fermentation comes to the end.

• Sauerkraut fermentation.
  

Any change to the above cycles of lactic acid production will alter the taste and quality of sauerkraut. As long as the proper amount of salt is added and the recommended temperatures are observed, the three bacteria strains will ferment cabbage in the proper sequence.