The Abilities of Different Lactic Acid Bacterial Stains to Deplete Nitrite Level in MRS and M17 Broth

Abstract

Nitrite is still regarded as essentially undesirable in foods. Therefore, it is necessary to keep its concentration under control for food safety. The current study was conducted to evaluate the ability of two reference lactic acid strains to deplete nitrite. Lactobacillus acidophilus ROO52 and Streptococcus thermophiles YC-180 were examined in De Man Rogosa and Sharpe (MRS) and M17 broth with standard sodium nitrite at 0.10 mg /mL and 1 mL (10-8 cells per mL) for each of the reference strains to determine the ability of these strains to eliminate nitrite during the fermentation period. A control group, MRS and M17 broth and standard nitrite without inoculum were used. The nitrite depletion was determined by a UV-Vis spectrophotometer. After 48 hours of fermentation, there were significant differences between residual nitrite levels of broth inoculated by Streptococcus thermophiles YC-180 compared to control and Lactobacillus acidophilus ROO52. Streptococcus thermophiles YC-180 depleted nitrite levels significantly (P˂0.05) from the initial concentration (0.10 mg/ml) to 0.02 mg/ml with a percentage (45%) after 48 hours compared to control and Lactobacillus acidophilus ROO52, which depleted nitrite levels from the initial concentration of 0.10 mg/ml to 0.04 mg/ml with a percentage (22.5%) after 48 hours. In conclusion, Streptococcus thermophiles YC-180 was more effective at nitrite depletion than Lactobacillus acidophilus ROO52. The reduction of nitrite occurs due to acid production and the enzymatic action of these bacteria.