传统发酵泡菜优势微生物及其代谢特性

采用平板计数法分析泡菜发酵过程中主要微生物的变化规律，并利用高效液相色谱仪、pH计等仪器分析底物、代谢产物和pH值的变化。结果表明：我国传统泡菜发酵过程中的主要微生物有乳酸菌、醋酸菌、酵母菌及霉菌；发酵7 d后，卤水的最终pH值由初始的5.7降至3.2；蔗糖作为发酵体系内的主要碳源，在整个发酵过程中被大量代谢利用，发酵7 d后，蔗糖浓度由初始的74.4 mmol/L变为18.4 mmol/L；而葡萄糖和果糖在发酵过程中没有明显被利用，其浓度分别维持在28.1 mmol/L和23.2 mmol/L；柠檬酸与苹果酸分别在24 h和12 h时达到最大浓度（3.4 mmol/L和8.9 mmol/L），然后下降，最后维持稳定，因此，发酵微生物对柠檬酸和苹果酸有一定的利用能力；乳酸是发酵过程中的主要代谢产物并且呈现稳定的增长趋势，其浓度由初始的5.6 mmol/L增长至149.6 mmol/L；乙酸和乙醇的产生则主要发生在泡菜的发酵前期。

Changes and Metabolic Characteristics of Main Microorganisms during Chinese Sauerkraut Fermentation

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.