Sodium citrate reduces residual levels of carbohydrates and increases bacterial counts in a fermented mixed vegetables medium

- The addition of citrate to a vegetable juice medium reduced the level of residual sugars following a lactic fermentation.
- Citrate supplementation increased viable counts of lactic acid bacteria,
- Concentrations of 150 mM citrate and above inhibited the lactic fermentation.

Incomplete sugar catabolism occurs in many traditional vegetable-based lactic fermentations, such as sauerkraut and kimchi. The goal of this study was to extend sugar catabolism and improve growth of a mixed lactic starter (Lactobacillus plantarum, Leuconostoc mesenteroides, Pediococcus acidilactici) by adding a citrate buffer salt or by external pH control. Fermentation of a vegetable juice medium (VJM) with external pH control (pH =5.6) enabled utilization of 92% of total sugars after 72 h at 20 °C. When 25-100 mM sodium citrate was added to the VJM, a 3.5-fold increase in viable counts of Leuconostoc mesenteroides occurred in fermented VJM and lower levels of residual sugars were obtained in the fermented product. These results suggest that addition of sodium citrate into VJM prior to fermentation could increase sugar catabolism as well as viable counts of lactic bacteria with some being potentially probiotic.