Junfei Chen

This study aimed to screen lactic acid bacteria (LAB) with enhanced antioxidant activity and evaluate their potential as starter cultures for dry-cured fermented sausages by assessing their effects on oxidative stability and physicochemical quality during processing. The antioxidant activities of different cellular fractions of five LAB strains were first compared, and the results indicated that the antioxidant activity was mainly associated with extracellular metabolites. Based on their good in vitro antioxidant activities and oxidative tolerance, Leuconostoc carnosum AMS1 and Lactiplantibacillus plantarum P4 were subsequently selected as starter cultures for sausage fermentation. Individual inoculation with AMS1 and P4 modulated the bacterial community structure during fermentation and reduced the abundance of opportunistic pathogens. Compared with the uninoculated control, starter inoculation accelerated acidification, reduced water activity, and positively modulated color and texture properties. Moreover, inoculation improved oxidative stability, as indicated by reduced thiobarbituric acid reactive substances (TBARS) levels and lipoxygenase (LOX) activity, and alleviated protein oxidative changes, as evidenced by lower carbonyl accumulation, reduced sulfhydryl group loss, and a lower increase in surface hydrophobicity. In conclusion, AMS1 and P4, particularly AMS1, showed potential as antioxidative starter cultures for dry-cured fermented sausages by improving physicochemical quality and oxidative stability during fermentation and maturation.

Fermented vegetables in Yunnan Province, China, harbor abundant microbial diversity. However, the development of indigenous starter cultures remains under-utilized. Genomic information regarding Leuconostoc (L.) mesenteroides isolates from this region is particularly scarce. To assess the genomic characteristics of eight L. mesenteroides isolates from traditional Yunnan fermented vegetables, we performed whole-genome sequencing and conducted a comparative analysis with 21 publicly available vegetable-derived genomes. Comparative genomic analysis revealed marked variation in genome size and plasmid content, and pangenome analysis indicated an open configuration. Core-genome multilocus sequence typing (cgMLST) of the eight indigenous isolates showed high allelic diversity, indicating a genetically heterogeneous and non-clonal population. Phylogenomic analysis revealed that the evolutionary relationships among the 29 strains were not strictly correlated with their vegetable sources, suggesting an influence from other factors, such as geographic origin and region-specific processing methods. Similar to the profiles of the 21 publicly available genomes, inactive prophages, intrinsic vancomycin resistance genes, and genomic island fragments were detected in eight isolates, whereas no known virulence genes were identified. Bacteriocin gene clusters varied among strains, while stress tolerance and probiotic-related genes were conserved. Overall, these results provide genomic indications relevant to the safety, adaptability, and fermentation potential of indigenous L. mesenteroides from Yunnan. However, because these functional traits are inferred solely from genomic predictions, subsequent experimental validation is essential to confirm their phenotypic properties and technological efficacy.

The properties of faba bean (Vicia faba L.) protein isolate (FPI) gels depend on their starting protein material and can be modulated by the addition of polysaccharides. In order to investigate the interplay between these two factors, commercial FPI (FPI₁) and FPI prepared in-house (FPI₂) were used to fabricate glucono-delta-lactone-induced gels, with or without dextran (DX) addition. FPI₁ exhibited lower solubility in water and a larger mean particle size, likely because it experienced extensive degradation due to the intense conditions involved in its preparation. The FPI₁ gel showed a similar water-holding capacity as the FPI₂ gel; however, its hardness was lower and viscoelasticity was higher. After DX addition, the hardness of both FPI gels decreased, while their water-holding capacity increased. Interestingly, DX addition decreased the viscoelasticity of the FPI₁ gel but enhanced the viscoelasticity of the FPI₂ gel. The microstructural analysis demonstrated that the density of the aggregation network decreased in the FPI₁ gel after DX addition but increased in the FPI₂ gel. This was consistent with the changes observed in the dominant protein interaction forces in these gels after DX addition. Overall, these findings have the potential to guide ingredient selection for the tailored preparation of FPI gels.