SUMMARY
In the present study, antimicrobial effects of traditional beverages produced from grapes such as traditional grape pickles, grape juice, home-made hardaliye, and commercially produced hardaliye were investigated using microdilution method against Staphylococcus aureus ATCC 6538P, Escherichia coli ATCC 25922, Salmonella Typhimurium NRRL B4420, Bacillus cereus ATCC 10876, Saccharomyces cerevisiae NRRL Y-12632, Lactobacillus acidophilus La-5 and L. rhamnosus LGG. In addition, total phenolic content was measured by the Folin-Ciocalteau method, and antioxidant activities of grape products were evaluated using DPPH assay. Results showed that grape containing beverages have antimicrobial effects on S. aureus, E. coli, S. typhimurium and B. cereus at various minimum inhibitory concentration (MIC) values in the range of 4.53-150 mg/mL. The lowest MIC value of 4.53 mg/mL was obtained against E. coli for home-made hardaliye. MIC values of the traditional grape pickles were determined as 4.69 mg/mL and 9.38 mg/mL against S.aureus and E.coli, respectively. On the other hand, traditional grape pickles showed weak inhibitory effects against B.cereus with MIC value of 150 mg/mL. The bactericidal effect of these grape products was not detected for any of the test microorganisms however traditional foods produced by using grapes were showed inhibitory effects at different concentrations against tested microorganisms except for probiotics and the yeast. The total phenolic contents of the grape products were within the range of 865.27-2193.08 mg gallic acid equivalent (GAE)/L. Free radical scavenging activities of grape samples ranged from 46% to 90% and the grape juice was found to have the highest antioxidant activity. In conclusion, grape beverages have the potential to act as a antimicrobial and antioxidant agents for use as a natural antimicrobial and antioxidant product in the food industry.