Bioactive, Physicochemical and Antimicrobial Properties of Koruk (Unripe Grape, Vitis vinefera L.) Products

In the study, the bioactive, physicochemical and antimicrobial properties of koruk juice and driedkoruk pomace were investigated. The total phenolic contents of koruk juice and pomace weredetermined as 1119.670 and 1182.170 mg GAE/L, respectively. Higher DPPH radical scavengingactivity found in koruk pomace, which was consistent with total phenolic contents. Organic acid,total sugar and ascorbic acid contents of koruk juice (3.44%, 4.737 g/L and 2.559 mg/100 mL) werehigher than koruk pomace (0.19%, 0.866 g/L and 0.242 mg/100 mL). The counts of TotalPsychrophilic Aerobic Bacteria and mold-yeast in pomace were determined as 0.694 and 1.016 logCFU/g, respectively, while no growth was observed in koruk juice. Koruk juice and pomaceindicated antimicrobial effect on all test microorganisms in the range of 31.3-500.0 µg/mL(Minimum Inhibition Concentration). The most sensitive bacteria to koruk juice were Bacilluscereus, while Pediococcus acidilactici was the most sensitive one to koruk pomace. Koruk juicealso showed bactericidal effect on all test cultures at concentration ranging between 250.0 and 500.0µg/mL (Minimum Bactericidal Concentration), koruk pomace was not showed bactericidal effecton Escherichia coli O157:H7, Salmonella Typhimurium, E. coli and B. cereus. This studydemonstrated that the koruk products could be used in food applications as natural antioxidant andantimicrobial substance.