Vegetable . Sauerkraut and pickles are examples of foods preserved by fermentation. Sauerkraut undergoes 3-5 stages of bacterial conversion in which sugars are converted to organic acids acid . salt , which is required to inhibit the growth of spoilage and pathogenic microorganisms , is added to shredded cabbage , and the mixture is stored in large vats , with air excluded by flexible covers .
Normally , the desired organisms are inoculated , though the natural flora may also be used . Some gas may be produced. Natural juice extracted by the added salt creates a brine . Cooler temperatures are preferred to help control the rate of conversion , which can take weeks , but very low temperature bacterial growth altogether.
Special cucumbers , bred to respond well to the conversion process , are converted to pickles in much the same way storage in large vats with added salt and other flavors , such as garlic. Elucidating the exact mechanisms of conversion and improving process control are still subjects of research , even for such family old products.