The potential of bacterial cultures to degrade the mutagen 2-methyl-1,4-dinitro-pyrrole in a processed meat model.

Processed meats are classified by the International Agency for Research on Cancer as category 1 because their consumption increase the incidence of colorectal and stomach cancers. Meat processing widely employs nitrite and sorbate as preservatives. When these preservatives are concomitantly used in non-compliant processes, they may react and produce the mutagen 2-methyl-1,4-dinitro-pyrrole (DNMP). This study aimed to evaluate the ability of different bacteria isolated from food matrices to biodegrade DNMP in in vitro reactions and in a processed meat model. A possible mechanism of biodegradation was also tested. In vitro experiments were performed in two steps. In the first one, only one strain out of 13 different species did not interact with DNMP. In the following step, an empirical conversion factor was calculated to assess the conversion of DNMP to 4-amino-2-methyl-1-nitro-pyrrole by the strains. The most efficient strains were Staphylococcus xylosus LYOCARNI SXH-01, Lactobacillus fermentum LB-UFSC 0017, and Lactobacillus casei LB-UFSC 0019, which yielded conversion factors of 0.62, 0.60, and 0.43, respectively. Thus, such strains were individually added to the processed meat model and completely degraded the DNMP. Moreover, S. xylosus degraded DNMP in less than 30 min. The enzymatic mechanism was evaluated using its cell-free extract. It showed that, in the aerobic system, reduction rates were 30.321 and 22.411 nmol/mg of protein/min using NADH and NADPH, respectively. A DNMP reductase was assigned to the extract and a potential presence of an oxygen insensitive nitroreductase type I B was considered. Thus, biotechnological processes may be an efficient strategy to eliminate the DNMP from meat products and to increase food safety.

Microbial biotransformation of N-nitro-, C-nitro-, and C-nitrous-type mutagens by Lactobacillus delbrueckii subsp. bulgaricus in meat products.

Processed meats are classified by the International Agency for Research on Cancer (IARC) as carcinogenic to humans. However, information on the responsible agents and the influence of industrial processing on the increased risk of cancer is still lacking. This study aimed to use cultures of Lactobacillus delbrueckii subsp. bulgaricus LB-UFSC 01 to biodegrade harmful C-nitrous, N-nitro, and C-nitro compounds in processed meat matrix. Firstly, positive results for ethylnitrolic acid (ENA) (>5.00 µg kg-1) and 2-methyl-1,4-dinitro-pyrrole (DNMP) (>12.0 µg kg-1) were obtained in mortadellas produced under different experimental conditions employing preservatives and antioxidants. Mortadellas containing nitrite and sorbate in the ratio of 8:1 (w/w) yielded the highest concentrations of mutagens. However, the treatment with the LB-UFSC 01 culture was able to modulate the harmful compounds in the mortadella samples. Several analytical methods employing liquid chromatography coupled to mass spectrometry and statistical models were employed to identify the metabolites and reaction routes during microbial biotransformation. For the first time, relevant information regarding the formation and degradation of ENA and DNMP in a processed meat model simulating real conditions was presented.

Interactions of preservatives in meat processing: Formation of carcinogenic compounds, analytical methods, and inhibitory agents.

Meat products are important for balanced diets because of their nutritional richness. However, noxious compounds may be formed by interactions among reactants and specific conditions in processed meats. N-nitroso compounds, heterocyclic aromatic amines, polycyclic aromatic hydrocarbons, 1,4-dinitro-2-methyl pyrrole (DNMP), and ethyl nitrolic acid (ENA) are among the main compounds of toxicological concern. This review corroborates the International Agency for Research on Cancer (IARC)'s decision to classify those foodstuffs as carcinogenic to humans. Furthermore, this paper also aimed at clarifying how noxious compounds are formed in meat products, as well as their health effects for consumers. The preservatives abuse and the use of forbidden additives may increase the formation of carcinogens. Risks are not only due to preservatives, since some compounds are formed during processing or digestion, without clear link to any additive. Regulation should set specific residue limits for other noxious compounds in meat products, such as DNMP and ENA. The scope of control programs should be extended instead of assessing the proper use of additives only. Thus, reliable analytical methods for the quantitation of carcinogens should be available. Fermentative and enzymatic processes for bioconversion are among the main strategies to solve these problems in foodstuffs. The use of antioxidants is the most common approach, because of its low cost and effectiveness. In the future, the IARC classification should rather consider different categories of processing, as well as the chemical and microbiological composition of meat products. Further studies are still required to clarify the increase on cancer risk due to the consumption of meat products and to elucidate the main mechanisms of carcinogenicity. Notwithstanding, such carcinogens cannot be neglected, but continuously investigated, including their health implications in relation to other foods.