Assessment of the Physicochemical Properties and Biological Activity of Vietnamese Single-Bulb Black Garlic

This study assessed the quality and biological activity of Vietnamese single-bulb black garlic (SBG) by investigating the effect of different temperatures (60, 65, 70, and 75 ?) on physicochemical properties during the heat treatment process. The optimal treating conditions accounted for the highest concentration of antioxidants were 70 C for 42 days. The SBG.70 had a higher content of reducing sugar, protein, flavonoid, and polyphenol in comparison with the white garlic and the others. Antioxidant activity of single-bulb white garlic and SBG were measured via DPPH, phosphomolybdenum, and H2O2 radicals, as well as a reduction potential. The antimicrobial activity was assessed by the multi-concentration dilution method; the sample treated at 70 ? displayed the strongest activity against four microbial strains with MIC values for S. aureus, P. aeruginosa, B. cereus, and C. albicans of 64, 128, 128, and 64 mu g/mL, respectively. Additionally, only two SBG samples aged at 70 C and 75 C were bacteriostatic to E. coli with MIC values of 32 and 64 mu g/mL, respectively.