Effects of garlic addition on bacterial communities and the conversions of nitrate and nitrite in a simulated pickle fermentation system

Garlic is a spice widely used in traditional pickle making. In this study, effects of garlic addition on bacterial communities and dynamic changes of nitrate and nitrite levels in a simulated pickle fermentation system were investigated under different conditions (with/without the inoculation of Lactobacillus plantarum or Escherichia coll.). The result showed that garlic addition efficiently enhanced the growth of Lactobacillus and Weissella while inhibited a lot of undesirable microorganisms during the fermentation. Kinetic analysis revealed that garlic addition and L. plantarum inoculation both significantly decreased the conversion of nitrate and eliminated nitrite peak, but led to much higher level of remaining nitrate (above 1000 mg/kg). Correlation analysis suggested that nitrite conversion was mainly related with the growth of lactic acid bacteria, while nitrate conversion depended more on other microorganisms (like E. coli). Based on these results, introducing safe microorganisms with relatively high nitrate reductase activities and balancing the conversions of nitrate and nitrite were suggested for safer pickle production.