Abstract:

Laboratory scale fermentations of Chinese sauerkraut were performed to investigate the changes in
microorganisms, the pH of the brine, the substrates and the metabolic products. The main microorganisms were monitored
using selective agar medium. The substrates and the metabolic products were analyzed by high performance liquid
chromatography. The results evidenced that the main microorganisms included lactic acid bacteria, acetic bacteria,
saccharomycetes and mycete. The pH was reduced from 5.7 to 3.2 after 7 days of fermentation. The utilization of sucrose
during the fermentation was strong, as indicated by a reduction from 74.4 to 18.4 mmol/L. However, glucose and fructose
were hardly metabolized by the cells and their final concentration were 28.1 mmol/L and 23.2 mmol/L, respectively. Critic
acid and malic acid were easily metabolized during the fermentation and their maximum concentrations, (3.4 and 8.9 mmol/L,
respectively) were observed after 24 and 12 h of fermentation followed by a decline until reaching a plateau. As the major
metabolic product, lactic acid was steadily increased from 5.6 to 149.6 mmol/L during the fermentation; moreover, the levels
of ethanol and acetic acid increased in the early stage of the fermentation process.

Key words: Chinese sauerkraut, lactic acid bacteria, fermentation, metabolism