Antimicrobial activity evaluation of black currant (Ribes nigrum L.) variety Čačanska crna juice and extract

Aim. This study aimed to evaluate and quantify the antimicrobial activity of lyophilized fruit juice (BCLJ) and waste extract (BCLW) obtained from the black currant (Ribes nigrum L.) variety Čačanska crna. Materials and method. The study was conducted using four Gram (+) (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis) and five Gram (-) bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis, Proteus mirabilis, Enterobacter aerogenes) as well as one yeast (Candida albicans). Cyanidin-3-O-glucoside, delphinidin-3-O-rutinoside and delphinidin-3-Oglucoside present in black currant were used as standards, so the second aim was to determine their influence on the total antimicrobial activity. Results. The tested samples showed moderate antimicrobial activity. The inhibitory effect of BCLJ was shown on all Gram (+) bacteria (B. cereus, E. faecalis, S. aureus), apart from L. monocytogenes, for which the extracts were not effective. It was noted that BCLJ did not suppress the growth of Gram (-) bacteria. Black currant waste extract on the other hand was shown to be efficient on Gram (+) as well as on Gram (-) bacteria. The results of minimum inhibitory concentrations MIC (MFC) of BCLJ and BCLW were 100 mg/mL and MBC was higher than 100 mg. The MIC/MBC (MFC) of standards were 0.13 - 0.5 mg/mL. Conclusion. Results indicate that these black currant lyophilizates might be potentially used as antimicrobial agents.