Microbiology and Enzymatic Kinetics of Sauerkraut
Sauerkraut is a product of lactic acid fermentation, where the physical and chemical properties of cabbage are transformed by a succession of microbial populations.
1. Microbial Succession Phases
The process begins with Leuconostoc mesenteroides, which produces $CO_2$ and lactic acid, lowering the pH rapidly and creating an anaerobic environment. As the acidity increases, these are replaced by more acid-tolerant species like Lactobacillus plantarum. This "Microbial Succession" is essential for developing the characteristic flavor and ensuring food safety.
2. Osmotic Dehydration
The addition of salt ($2–3$%) is a critical technical step. Salt draws out the cellular water from the cabbage through Osmosis, creating a brine. This inhibits the growth of "putrefactive" bacteria (spoilage organisms) while selecting for the salt-tolerant lactic acid bacteria.
3. Isothiocyanate Formation
During the fermentation process, enzymes (myrosinase) break down glucosinolates in the cabbage into Isothiocyanates. These are bioactive compounds with significant antimicrobial properties. The document highlights that the temperature must be maintained between $18–22$°C; higher temperatures can lead to "softening" of the cellulose structure due to excessive pectinase activity.