Impact of malolactic fermentation with Lactobacillus plantarum on volatile compounds of sea buckthorn juice

Malolactic fermentation using sea buckthorn (Hippophae rhamnoides) juice as raw material was performed with six different strains of Lactobacillus plantarum. Increasing juice pH from 2.7 to 3.5 or adapting cells to low pH (i.e., acclimation) prior to inoculation allowed malolactic fermentation with all tested strains. Moreover, reducing pH of the growth medium from 6 to 4.5 with l-malate had little or no impact on biomass production. Volatile profile of sea buckthorn juice was analyzed with HS-SPME-GC-MS before and after fermentation. A total of 92 volatiles were tentatively identified and semi-quantified from sea buckthorn juice, majority of which were esters with fruity odor descriptors. Esters and terpenes were decreased in both inoculated and control juices during incubation. Microbial activity increased the levels of acetic acid (vinegar like), free fatty acids (cheese like), ketones (buttery like), and alcohols with fruity descriptors. Conversely, aldehydes associated with green aroma were decreased as a result of fermentation. Juices fermented with DSM 1055 had the highest acid and alcohol content, while fermentation with DSM 13273 resulted in the highest content of ketones. Compared to inoculation with other strains, fermentation with strains DSM 16365 and DSM 100813 resulted in rapid malolactic fermentation, less production of volatile acids, and lower loss of esters and terpenes important for natural sea buckthorn flavor.

Automated summary

Malolactic fermentation using sea buckthorn juice as raw material was successfully carried out with six different strains of Lactobacillus plantarum. Adapting cells to low pH or increasing juice pH facilitated fermentation. Analysis of volatile compounds in the juice pre and post fermentation showed changes in esters, terpenes, acids, alcohols, and aldehydes, with certain strains leading to different levels of these compounds.