Lactococcus lactis: an original producer of volatile compounds during the fermentation of mashed cucumber

Fermented cucumber is popular around the world, especially in Southeast Asia. In this study, we fermented mashed cucumber with several strains harvested from fermented vegetables collected in various markets in Phnom Penh. Strains belonging to different families of Lactic Acid Bacteria were selected for fermentation: the homolactic Lactococcus lactis and Pediococcus pentosaceus, the heterolactic Limosilactobacillus fermentum, and the facultative heterolactic Lactiplantibacillus plantarum and Lactiplantibacillus pentosus. The fermentation of mashed cucumber was conducted for one day. Volatile compounds were analyzed using the HS-SPME-GCMS method. One strain behaved differently from the others. Indeed, L. lactis grew more slowly than the others (reaching 10⁷ CFU/g compared to other strains, which reached 10⁸ CFU/g after one day of fermentation). The results showed that the number of various volatile compounds of L. lactis strain was significantly higher than fermentation with the other strains. The main difference was the number of esters, especially acetate and ethyl ester. However, despite the higher diversity of compounds, the global concentration of volatile compounds was comparable to the concentration obtained with other strains. Thus, this finding provides valuable information about the activity of the L. lactis strain, which exhibits esterification in green vegetables, producing more diverse ester compounds.