Xuefei Shao,Baocai Xu,Hui Zhou,Conggui Chen,Peijun Li
The mechanism of decreasing N- nitrosodimethylamine (NDMA) by Lactobacillus pentosus R3 isolated from Chinese dry sausage was assessed in a model system. The model system was devised using a DeMan-Rogosa and Sharp-ferrous sulfate broth supplement with NDMA or its precursors. The results showed that inoculating L. pentosus R3 could significantly decrease the content of NDMA ( P < 0.05). The NDMA precursors (dimethylamine and putrescine) were found to be decreased by L. pentosus R3 ( P < 0.05). Nitrite was degraded to nitrosonium cation by acidolysis, which may promote the formation of NDMA. Direct degradation of NDMA by L. pentosus R3 was also observed. The strain exhibited antioxidant activities , including Fe 2+ chelating activity, which may be responsible for inhibiting the formation reaction and decreasing the precursors of NDMA. Thus, L. pentosus R3 decreased the content of NDMA possibly by three ways: inhibition of the formation reaction, decrease in precursors (DMA and putrescine) and direct degradation. It is interesting to understand the mechanism of decreasing NDMA by L. pentosus R3 to improve the safety of fermented meat products .
The objective of this study was to evaluate the ability of five strains of meat-borne bacteria to decrease N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) and to elucidate the mechanism in Mann-Rogosa-Sharp (MRS) broth. Lactobacillus pentosus R3 was found to be the most effective in decreasing the concentration of the two N-nitrosamines (NAs) in MRS broth, with a rate of 22.05% for NDMA and 23.31% for NDEA. The concentration of the two NAs could not be reduced by either extracellular metabolites or intracellular extracts of Lb. pentosus R3 (P > 0.05), and proteinaceous substances in the cell debris were found to be responsible for the decrease. These were surface-layer proteins (SLPs) located on the cell wall. Therefore, the decrease in NDMA and NDEA by Lb. pentosus R3 is associated with its SLPs. Lb. pentosus R3 may be developed as a starter culture in the production of fermented foods with lower NAs.
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