Impact of Lactic Acid Bacteria on the Flavor Profile of Salami and Role of Microbial Diversity and Functional Gene

Abstract

Salami sausage is a fermented meat product that is appreciated by consumers in most countries. Starter culture plays a key factor in affecting its quality. The present study screened four lactic acid bacteria (LAB) H1-5, N102, YL-1, and YL-2 strains with excellent fermentation characteristics based on their acid production, nitrite degradation, and bacteriostatic capacity. These bacterial strains were applied to make salami sausage, which reduced pH to 5.2. In groups H1-5 and YL-1, key flavors including linalool, 1-octen-3-ol, 3-methylbutyric acid, butyric acid, hexanal, heptanal, phenylacetaldehyde, 2-methylbutanol aldehydes, and p-cresol were detected. The YL-1 salami shows high concentrations of linalool, 1-octen-3-ol, and 3-methylbutyric acid with a concentration of 0.15, 0.04, and 1.08 mg/kg, respectively. Based on the metagenomic analysis, the salami sausage group YL-1 shows a high count of LAB strains mainly Lactobacillus rhamnosus accounting for 76.81% gene count over H1-5 salami. Through species and function contribution analysis, it was confirmed that YL-1 contributes to most of the metabolic functions including amino acid, carbohydrate, and lipid biosynthesis pathways based on the gene set analysis on the KEGG pathway. A total of 10 genes regulating metabolism and enzymes were obtained from YL-1 gene mining. Other metabolic pathways including valine, leucine, and isoleucine degradation, phenylalanine metabolism, and toluene degradation contribute to aromatic amino acids increase in the YL-1 sausage sample. It shows that YL-1 contributes high functional application in sausage fermentation and can be used as a potential key object in subsequent research to further clarify its functional application.