Purpose: In order to develop soy sauce and increase its functionality, by adding black garlic extract. Methods: We compared quality characteristics and antioxidant activity of 20 days aging black garlic soy sauce from mixed manufacturers with raw soy sauce (commercial fermented soy sauce) and different ratio of black garlic extract (65 Brix, 0.3-5.0%). Results: The salt content of the black garlic extract (0.3-5.0%) added soy sauce were 12.35-12.77%. The pH was lowered to 4.99, and acidity was increased to 2.12%, depending on the increase in black garlic extract added ratio. The crude protein and total nitrogen contents were 6.23-6.62% and 1.10-1.16%, respectively, and content of amino form nitrogen was 0.52-0.53%, without significant differences between experimental groups. Contents of reducing sugar and free sugars (fructose and glucose) tended to be higher with higher mixing ratios of black garlic extract. Total phenolic compounds and flavonoids contents were significantly increased in the 3% and 5% black garlic extract addition group. At concentrations of 62.5, 125, 250, 500, 1,000 and 2,000 µg/mL, the DPPH and ABTS radical scavenging activity of the polysaccharides isolated from control soy sauce and 5% black garlic extract added soy sauce showed higher correlation with their concentration. Conclusion: These results, confirmed that the soy sauce produced by adding more than 3% of black garlic extract has high antioxidant activity.

In this study, the quality characteristics of the representative domestic garlic varieties in Korea (Namdo, Daeseo, Hongsan, and Uiseong garlic) were compared and their changes according to the aging process of black garlic were investigated. Each garlic sample was aged for 15 days according to the manufacturing process of black garlic. The total phenolic compound contents were 85.2-109.7 mg GAE/100 g in raw garlic samples, which increased with the aging period, and Hongsan garlic showed the highest content in both raw and aged black garlic. The content of alliin was 848.3-1,087.5 mg/100 g in raw garlic samples, and it decreased significantly on the 5th day (7.3-20.6 mg/100 g) in aged garlic. The contents of GSAC (γ-glutamyl-S-allyl-cysteine) and GS1PC (γ-glutamyl-S-1-propenyl-l-cysteine) in raw garlic samples were 202.1-541.0 mg/100 g and 311.1-474.3 mg/100 g, respectively, but gradually decreased during the aging process. On the other hand, the SAC (S-allyl-cysteine) and S1PC (S-1-propenyl-l-cysteine) contents of raw garlic were very low in all four varieties, but they were highest on the 5th day of aging and tended to decrease thereafter. On the 5th day of aging, the SAC content of Namdo garlic (208.0 mg/100 g) was highest (p<0.05), and S1PC content was significantly higher in Uiseong garlic (66.2 mg/100 g) than the others.