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

Abstract

<p>Malolactic fermentation using sea buckthorn (<i>Hippophaë rhamnoides</i>) juice as raw material was performed with six different strains of <i>Lactobacillus plantarum</i>. 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.</p>