Antimicrobial activity of berries extracts of four Ribes species, their phenolic content and anthocyanin composition

Phenolic compounds are widespread in berries and determine their antimicrobial activity. The aim of our study was to establish the amounts of phenolic compounds and the anthocyanin composition in berries of four Ribes species, and to evaluate the effect of berry extracts on the growth of common Gram-positive and Gram-negative bacteria, and also yeasts isolated from food processing plants. The phenolic content and anthocyanin composition were estimated spectrometrically and by HPLC, respectively. The highest amount of phenolic compounds, and also anthocyanins, was found in extracts of R. aureum 'Corona'. The anthocyanin content was the lowest in berries of R. aureum Au Gs-5, with equal amounts of delphinidins and cyanidins. Delphinidins were predominant (68.6%) in berries of R. nigrum 'Ben Tirran', while cyanidins dominated in R. uva-crispa. The berry extracts of R. aureum Au Gs-5 and R. uva-crispa 'Lusiai' had the largest growth-suppressing effect on yeasts and most of the bacteria tested. All of the berry extracts suppressed the growth of pathogenic and conditionally pathogenic bacteria. The industrially important Lactococcus lactis was the most resistant to the Ribes berry extracts. There was no correlation between the amount of anthocyanins in the extracts and their antimicrobial properties. Extracts with a lower anthocyanin-to-phenolics ratio more effectively inhibited the growth of bacteria.