In vitro metabolism of elderberry juice polyphenols by lactic acid bacteria.

In this study, ten strains of Lactobacillus were used to assess the in vitro metabolism of elderberry juice polyphenols. Total polyphenolic compounds increased after starter addition, especially with three L. rhamnosus and one L. plantarum strains, of dairy origin: quercetin-3-O-rutinoside was the most abundant compound (from 39.02 ± 5.28 to 127.56 ± 11.34 µg/mL) and hydroxycinnamic acids, flavonols and anthocyanins reached the highest amounts. When L. plantarum were used phenyllactic acids presented a value of 7.05 ± 2.38 µg/mL, while in the other samples it was around 5.56 ± 1.65 µg/mL. Hydroxycinnamic and hydroxybenzoic acids were subjected to lactic acid bacteria metabolism: caffeic and protocatechuic acids were consumed during fermentation while dihydrocaffeic acid and catechol were produced. Anthocyanins increased in a strain-specific way. So, by this study we highlighted that dairy strains can produced (phenyllactic acids), modified (hydroxycinnamic acids) or increased (flavonols glycosides and anthocyanins) phenolic compounds.