Antioxidant Activity of Various Soluble Melanoidins Isolated from Black Garlic after Different Thermal Processing Steps

To gain insight into the antioxidant activity of various soluble melanoidins isolated from black garlic after different thermal processing steps, the antioxidant activity was evaluated. Black garlic was produced in a ripening chamber using a programmed stepwise heating schedule as follows: Step 1, 90°C and 100% (RH) for 34 h; Step 2, 60°C and 60% RH for 6 h; Step 3, 75°C and 70% RH for 48 h; Step 4, 70°C and 60% RH for 60 h; Step 5, 65°C and 50% RH for 192 h. The melanoidins isolated from black garlic after the different thermal processing steps were divided into different melanoidin fractions, i.e., melanoidins, pure melanoidin, bound melanoidin compounds (BMC). The antioxidant activity of the melanoidins bound to low molecular weight compounds (BMC fraction) was generally higher than those of the pure melanoidins. Notably, the antioxidant activity of various soluble melanoidins differed according to the thermal processing steps. The results may be useful in predicting the behavior of various soluble melanoidins during thermal processing of garlic.