Bacterial community and quality characteristics of the fermented potherb mustard (Brassica juncea var. multiceps) under modified atmospheres.

Bacteria play a vital role in vegetable fermentation and preservation. However, the influence of a modified atmosphere (MA) on the storage of fermented vegetables has rarely been reported. In this study, the bacterial community composition and quality of fermented potherb mustard under carbon dioxide (CO2) and nitrogen (N2) conditions were investigated under 7% salt storage at room temperature (18-20 °C). Analysis of 16S rRNA gene sequencing showed dominant bacterial genera Halomonas and Psychrobacter were present under natural air conditions, while Lactobacillus was the major genus present under MA conditions. The bacterial communities differed significantly between MA and natural air conditions, and demonstrated wide diversity. In addition, titrable acidity (TAA) and nitrite contents were significantly reduced under MA conditions as compared to natural air condition. However, N2-MA resulted in TAA values that were rarely exceeding the ripe level 0.3% lactic acid. Thus, CO2-MA may represent a valuable approach to avoid the excessive acidification or incompletely ripe of the fermented vegetable. Present data also indicated better color and higher firmness of the fermented product under CO2 conditions when compared to N2 conditions. These results indicated that CO2-MA has a positive influence on bacterial community and the quality of fermented potherb mustard, which enlighted a new strategy for enhancing the quality of fermented vegetables.