Bacteria Control

Bacteria Control

Sauerkraut is made by lactic acid bacteria that break sugar into lactic acid, carbon dioxide (CO2, soda gas) and a little amount of alcohol. Because cabbage contains water, sugar and many nutrients it is a perfect media for all types of bacteria to grow, some of them we try to avoid. Heat treatment will surely kill undesirable bacteria, but it also will kill lactic acid bacteria that we need, so this method does not apply here.
pH acidity of fresh cabbage is at around pH 7.0 which is at neutral point of acidity scale. This makes cabbage an ideal food for microorganisms as it contains water, sugar, proteins, minerals and all nutrients. We control bacterial growth using the following steps:

• Washing.
• Applying salt.
• Elimination of oxygen.

Washing. Cabbage is in a direct contact with soil which is loaded with all types of microorganisms. Most microorganisms are present on outside green leaves which are usually discarded. One gram of fresh cabbage may contain 250,000 bacteria and this number may grow to 1,000,000 during storage. So, the first step is to wash the cabbage well as this action removes plenty of microorganisms. If ingredients such as apples or carrots will be added, thy must be thoroughly washed as well.
Salt. Salt is needed for two reasons:

• To remove the cabbage juice and nutrients from each cell and make it available as food to lactic acid bacteria. Bacteria will not eat dry cabbage leaves, however, they will absorb filled with nutrients juice. Bacteria are like sponge, they don’t pick up the dry matter but will suck up anything wet.
• To keep other bacteria away. A moderate amount of salt does not bother sauerkraut bacteria (lactic acid), however, other bacteria types find such conditions intolerable.

As lactic acid bacteria start to produce slowly lactic acid, this becomes even worse for other bacteria types, as generally bacteria hate acid. Of course lactic acid bacteria are not bothered by moderate amounts of acid at all. This combination of salt and increasing amount of acid inhibits growth of other bacteria and makes sauerkraut more stable as the fermentation advances
To make high quality sauerkraut salt is applied at 2 – 2.5% in relation to the weight of the sliced cabbage. Decreasing salt levels will create quality problems, going below 1.5% will rot the cabbage. Spoilage bacteria will survive such a low salt level and will take over the process and will spoil the product.
Absence of Oxygen. When container as packed with cabbage all microorganisms start to compete for food. Salt inhibits some of them, but many others need oxygen to survive, for example molds. Eliminating oxygen is accomplished by a few methods:

• Packing container hard with shredded cabbage.
• Slicing cabbage thinner, this allows to pack more cabbage and disperse more air.
• Keeping cabbage submerged in brine (using weights).
• Using water channel fermented crocks or air lock glass jars.

Eliminating oxygen preserves vitamin C from oxidizing and losing its strength.
Fermented sauerkraut exhibits pH at around 3.5 and will keep in cool conditions for a very long time, as long as this pH level is maintained.