Abstract: This study aimed to explore the inhibition mechanism of Lactobacillus starter culture PRO-MIX5 (containing Staphylococcus xylosus + Lactobacillus sake + Lactobacillus paraplantarum), which had been obtained in our previous study and found to effectively inhibit the formation of N-nitrosamines in Harbin red sausage, on the formation of N-nitrosamines. PRO-MIX5 was cultured in both minced meat medium and MRS medium for stepwise screening using nitrite degradation system and N-nitrosodimethylamine (NDMA) generation system. As a result, we found that the cell debris but not the metabolites, intracellular enzymes or whole cells could inhibit NDMA formation. Furthermore, the effect of the type of inducer added to MRS medium and the amount of cell debris added on the inhibition of NDMA formation was investigated. Finally, confirmation experiments were conducted by adding the cell debris obtained under optimized conditions at levels of 0.05%, 0.25% and 0.5% (on a wet mass basis) to Harbin red sausage and bacon. The results showed that the cell debris of PRO-MIX5 inhibited NDMA formation. A good inhibition effect was observed by culturing PRO-MIX5 in MRS medium containing 9 N-nitrosamines at a concentration of 0.04 μg/mL. Among the three addition levels, the cell debris at 0.05% showed the highest inhibition effect on the formation of the N-nitrosamines in both Harbin red sausage and bacon with inhibition percentages of 41.04% and 13.83%, respectively, and therefore its application could give good results.

Key words: lactic acid bacteria, N-nitrosamine, nitrite, N-dimethylnitrosamine, Harbin red sausage, bacon