Sample AOX (%) Free radical scavenging activity IC50 EC50 ARP Natural fermentation         CNF1 54.55 ± 1.16d 3.37 ± 0.05b 113.93 ± 1.82b 0.88 ± 0.01b TNMX 65.65 ± 0.39a 5.18 ± 0.43a 175.28 ± 14.54a 0.57 ± 0.05c Pure culture fermentation         CNF2  58.49 ± 2.30c 2.70 ± 0.01c 91.30 ± 0.40c 1.10 ± 0.00a TNB51 62.12 ± 0.95b 3.27 ± 0.01bc 110.74 ± 0.41bc 0.90 ± 0.01b *Data are means ± S.D. of triplicate measurements. Means in the same column with different letters were significantly different (P<0.05). **CNF1, CNF2 = Cooked non-fermented soybeans prepared by boiling and autoclaving, respectively; TNMX, TNB51 = thua nao fermented by naturally occurring bacteria and B. subtilis TN51. ***AOX = Antioxidant activity determined by the β-carotene linoleic acid system at 10 mg/mL of dried sample extracts; IC50 = Half maximal inhibitory concentration (mg/mL of sample extract); EC50 = Efficiency concentration (mg/mg DPPH); ARP = antiradical power.

Table 2: Antioxidant activities of methanolic extracts of cooked non-fermented soybeans (CNF) and thua nao.