Food Science Research Unit, USDA-Agricultural Research Service, SEA, Raleigh, NC, USA.
Bioinformatics Research Center, North Carolina State University, Raleigh, NC, USA.
J Appl Microbiol. 2020 Jun;128(6):1678-1693. doi: 10.1111/jam.14597. Epub 2020 Feb 21.
Differences in the bacterial population of cucumber fermentations brined with no salt, 100 mmol l (1·1%) calcium chloride (CaCl ) or 1·03 mol l (6%) sodium chloride (NaCl) were studied.
Changes in the microbiology and chemistry of commercial and laboratory scale cucumber fermentations occurring as a function of time were monitored using colony counts and metagenetic analysis, and a pH probe and high-performance liquid chromatography analysis respectively. Dissolved oxygen and carbon dioxide content were monitored in commercial fermentations. Fermentations brined with calcium chloride (CaCl ) or no salt sustained faster microbial growth and reduction in pH than those brined with 1·03 mol l NaCl. Leuconostoc, Lactococcus and Weissella dominated in fermentations brined with no salt or 100 mmol l CaCl on day 1 as compared to Weissella and enterobacteria in fermentations containing 1·03 mol l NaCl. Lactobacilli dominated all fermentations by the third day, regardless of salt type, and was followed, in relative abundance by Pediococcus, Leuconostoc, Lactococcus and Weissella. From 84 to 96% of the population was composed of Lactobacillus by day 7 of the fermentations, except in the no salt fermentations in which a mixed population of LAB remained. The population of LAB found in commercial cucumber fermentations brined with 100 mmol l CaCl (n = 18) or 1·03 mol l NaCl (n = 9) mimicked that of laboratory fermentations. A declining population of aerobes was detected in commercial fermentations brined with CaCl on day 1.
A reduced NaCl content in cucumber fermentation enhances microbial diversity.
This study fills a knowledge gap and aids in the design of improved reduced NaCl cucumber fermentations.
研究了分别用无盐、100mmol l（1·1%）氯化钙（CaCl ）或 1·03mol l（6%）氯化钠（NaCl）腌制的黄瓜发酵中细菌种群的差异。
通过菌落计数和宏基因组分析，以及 pH 探头和高效液相色谱分析，分别监测商业和实验室规模黄瓜发酵中微生物学和化学随时间的变化。在商业发酵中监测溶解氧和二氧化碳含量。用氯化钙（CaCl ）或无盐腌制的发酵比用 1·03mol l NaCl 腌制的发酵维持更快的微生物生长和 pH 降低。与含有 1·03mol l NaCl 的发酵相比，在无盐或 100mmol l CaCl 腌制的发酵中，第 1 天优势菌为肠球菌、乳球菌和魏斯氏菌。第 3 天，无论盐的类型如何，乳酸菌都主导了所有的发酵，其次是肠球菌、乳球菌、魏斯氏菌和肠球菌。在发酵的第 7 天，84%至 96%的菌群由乳酸菌组成，除了无盐发酵中仍存在混合 LAB 菌群外。在商业黄瓜发酵中用 100mmol l CaCl （n=18）或 1·03mol l NaCl （n=9）腌制的 LAB 菌群与实验室发酵相似。在第 1 天，用 CaCl 腌制的商业发酵中检测到需氧菌数量下降。
减少黄瓜发酵中的 NaCl 含量可提高微生物多样性。
本研究填补了知识空白，有助于设计改进的低盐黄瓜发酵。
