Nitrite reduction in fermented meat products and its impact on aroma

The role of coagulase-negative staphylococci on aroma generation of fermented sausage

Fermented sausages are popular meat products with many different varieties. The aroma of fermented sausages depends on the metabolic activities of microbiota, mainly involving lactic acid bacteria and catalase-positive cocci, the group of coagulase-negative staphylococci (CNS) in particular. Regarding staphylococci, this work elucidated their generation of aroma precursors from hydrolase, metabolic activities contributing to aroma development, antioxidant effects that improve aroma via preventing excessive lipid oxidation. The metabolic pathways of staphylococci that play a role in aroma formation involve carbohydrate fermentation, amino acid degradation, fatty acid β-oxidation, and esterase activities. Their antioxidant activities are associated with superoxidase dismutase and catalase activities, as well as the production of antioxidant peptides. Processing conditions may influence CNS communities and affect aroma characteristics of fermented sausages. Implementation of genome sequencing and editing to select and customize CNS with specific biosynthetic metabolic pathways was proposed forward, offering a great potential for enhancing aroma development during sausage fermentation.

Biodegradation of chemical contamination by lactic acid bacteria: A biological tool for food safety

Chemical pollutants such as mycotoxins and pesticides exert harmful effects on human health such as inflammation, oxidative stress, and cancer. Several strategies were applied for food decontamination, including physicochemical and biological strategies. The present review comprehensively discussed the recent efforts related to the biodegradation of eight food chemical contaminants, including mycotoxins, acrylamide, biogenic amines, N-nitrosamines, polycyclic aromatic hydrocarbons, bisphenol A, pesticides, and heavy metals by lactic acid bacteria (LAB). Biological detoxification by LAB such as Lactobacillus is a promising approach to remove the risks related to the presence of chemical and environmental pollutants in foodstuffs. It is a safe, efficient, environmentally friendly, and low-cost strategy to remove hazardous compounds. LAB can directly decrease these chemical pollutants by degradation or adsorption. Also, it can indirectly reduce the content of these pollutants by reducing their precursors. Hence, LAB can contribute to reducing chemical pollutants in contaminated foods and enhance food safety.

Evaluation of the effects of compound curing agents on the lipid profiles and volatile flavors in Nuodeng ham based on lipidomics and GC-IMS analysis

Eighteen raw legs were evenly divided into two groups and salted with 100% NaCl and compound curing agent (60% NaCl + 40% KCl + 90 mg/kg NaNO2) to investigate the effect of compound curing agent on lipid metabolites and volatile flavor compounds in Nuodeng ham. The results of UHPLC-QE-MS and GC-IMS combined with multivariate statistical analysis showed that 27 lipid metabolites and 30 characteristic volatile flavor compounds were identified as characteristic markers in different treatment groups. The compound curing agent promoted the release of TG, SQDG, Hex1Cer, and LPC in Nuodeng ham, and accelerated the formation of volatile compounds such as 2-propanone, nonanal-d, gamma-butyrolactone, ethhyl acetate and benzeneacetaldehyde et al. Through correlation analysis, ketones were positively correlated with some PUFAs and negatively correlated with most MUFAs. Processing Nuodeng ham with compound curing agents has a positive effect on improving its quality. These findings provide a scientific theoretical basis for the development and utilization of compound curing agent.

Effects of lactic acid bacteria and coagulase-negative staphylococci on dry-fermented sausage quality and safety: Systematic review and meta-analysis

The meta-analysis aim was to confirm and quantifying the influence of starter cultures on microbiological and physical-chemical parameters of dry-fermented sausages at the end fermentation stage. The literature search yielded 1194 citations, and 77 studies with 178 experiments were eligible and included in the meta-analysis, a random-effects model was used to estimate the pooled weighted mean difference (MD) with 95% confidence interval (CI).The use of starter culture in dry-fermented sausages significantly reduced pH (MD: -0.364; CI: -0.414; -0.319), moisture (MD: -1.443; CI: -1.931; -0.955), aw (MD: -0.011; CI: -0.017; -0.006), Enterobacteriaceae count (MD: -1.119; CI: -1.293; -0.945), yeasts and molds count (MD: -0.351; CI: -0.691; -0.084), and increased color component a* (MD: 0.859; CI: 0.266;1.452), color component L* (MD: 1.288; CI: 0.433; 2.143), LAB count (MD: 0.981; CI: 0.696;1.267), Staphylococci count (MD: 0.484; CI: 0.293; 0.675) and TVC (MD: 0.529; CI: 0.098; 0.959). The results of the sub-analysis suggest that the addition of LAB and LAB/CNS inocula have a greater effect on the physico-chemical and microbiological parameters studied in this work. In the meta-regression analysis, a positive linear relationship was found in starter culture sausages in comparison with control batch between LAB count and the dose of starter culture added, and in the pH and Enterobacteriaceae count with the passage of fermentation days. In contrast, a negative linear relationship was found between redness and increased casing diameter of the sausages. Therefore, our work shows impact that addition of starter cultures has on safety and quality of dry-fermented sausages.

A Review on the Role of Lactic Acid Bacteria in the Formation and Reduction of Volatile Nitrosamines in Fermented Sausages

Nitrosamines are N-nitroso compounds with carcinogenic, mutagenic and teratogenic properties. These compounds could be found at certain levels in fermented sausages. Fermented sausages are considered to be a suitable environment for nitrosamine formation due to acid formation and reactions such as proteolysis and lipolysis during ripening. However, lactic acid bacteria (spontaneous or starter culture), which constitute the dominant microbiota, contribute significantly to nitrosamine reduction by reducing the amount of residual nitrite through nitrite degradation, and pH decrease has an important effect on the residual nitrite amount as well. These bacteria also play an indirect role in nitrosamine reduction by suppressing the growth of bacteria that form precursors such as biogenic amines. In recent years, research interest has focused on the degradation or metabolization of nitrosamines by lactic acid bacteria. The mechanism by which these effects are seen has not been fully understood yet. In this study, the roles of lactic acid bacteria on nitrosamine formation and their indirect or direct effects on reduction of volatile nitrosamines are discussed.