Malolactic fermentation using sea buckthorn (Hippophaë 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 in sea buckthorn
juice, majority of which were esters with fruity odor descriptors. Esters and
terpenes with mainly fruity descriptors were decreased in both inoculated and control
juices. 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 volatile acids, and lower loss of esters and terpenes important for natural
sea buckthorn flavor.