Antioxidant, Antibacterial and Color Analysis of Garlic Fermented in Kombucha and Red Grape Vinegar

Garlic, in different types, is a very common food ingredient all over the world. Traditionally, garlic is fermented in grape vinegar to produce garlic pickles; in this study, to produce a novel fermented food, garlic was fermented in kombucha beverage; then, antibacterial and chemical properties and color changes of garlics fermented in kombucha and vinegar were compared with each other and those of fresh garlic.
Material and Folin-Ciocalteu assay was performed to evaluate total phenolic contents; free radical scavenging activity was evaluated using 2,2- diphenyl-1-picrylhydrazyl. Disk diffusion method was performed to measure inhibitory activity against testing bacteria. A digital method was designed for color analysis. All data were statistically analyzed by ANOVA test at significant level of (p≤0.05).
Results and Fresh garlic extract had the highest inhibitory effect (mean 27.7 mm) against tested bacteria; kombucha fermented garlic showed bigger inhibition zone (mean 21.7 mm) than vinegar fermented garlic (mean 17.9 mm). Anti-staphylococcus aureus activity of fresh garlic was stronger than gentamycin and amoxicillin; inhibitory effect of garlic extracts against tested bacteria was significant in comparison with standard antibiotics. Fresh-garlic extract contained highest amount of phenolic contents; fermentation of garlic in kombucha decreased phenolic content of garlic bulbs by 1.92% and IC50 factor for antioxidant activity was 10.25% higher than fresh garlic; fermentation in vinegar reduced 21% of phenolic contents and IC50 obtained 47.4% higher than fresh garlic. Fermentation of garlic reduces the density of colors and luminosity, but the reduction in garlics fermented in vinegar is more than in kombucha. Appearance of vinegar fermented garlic changed to yellowish and kombucha inclined the color to reddish. Fermentation of garlic in kombucha provides better preservation of biological properties of garlic than in grape vinegar.