Effect of Levilactobacillus brevis and Limosilactobacillus fermentum combined with carrot powder on the quality, safety, and microbial community of dry-fermented sausages

Sodium nitrite is conventionally used in dry-fermented sausages to enhance quality, but its potential to form carcinogenic nitrosamines raises significant health concerns. This study aimed to evaluate the combined effect of Levilactobacillus brevis CHOL1, Limosilactobacillus fermentum 1.1880, and 1% carrot powder as a natural “clean label” alternative to nitrite in dry-fermented sausages. Three formulations were compared: a control (C), a group inoculated with the combined starter cultures and carrot powder (M), and a group with 100 mg/kg sodium nitrite (Y). The results demonstrated that Group M exhibited significant reductions in pH, water activity, and lipid oxidation, as measured by thiobarbituric acid reactive substances (TBARS), compared to the control. Textural analysis revealed that the co-addition mitigated excessive hardness and chewiness, providing a softer and more desirable texture. Furthermore, Group M achieved superior sensory scores in color, flavor, and overall acceptability, which were consistent with its significantly higher a*/b* values compared with the control. High-throughput sequencing indicated that Lev. brevis established absolute dominance during fermentation, effectively suppressing the growth of spoilage bacteria such as Photobacterium phosphoreum . Crucially, the combination treatment significantly inhibited the accumulation of total biogenic amines (including histamine and putrescine) and N-nitrosamines compared to the control (p < 0.05). In conclusion, inoculating dry-fermented sausages with Lev. brevis CHOL1, Lim. fermentum 1.1880, and carrot powder is an effective strategy to optimize textural and sensory properties while simultaneously enhancing the chemical and microbiological safety of the product.