2.9.2. Trolox Equivalent Antioxidant Capacity (TEAC) Assay

The trolox equivalent antioxidant capacity (TEAC) assay was carried out to determine the free radical scavenging capacity using ABTS<sup>+</sup> according to the method previously reported [28]. ABTS stock solution was prepared by mixing 7 mM ABTS and 2.45 mM potassium persulfate in a ratio of 1:1 (*v*/*v*) and then incubated at room temperature (23 ± 1 ◦C) in the dark for at least 16 h. The ABTS working solution was prepared by dilution of the stock solution with 80% ethanol before use, and then the absorbance at a wavelength of 734 nm was adjusted to 0.7 ± 0.05. The blank control is a mixture of 3.9 mL ABTS working solution and 0.1 mL of 80% ethanol. The spice extract sample (0.1 mL) was diluted with 80% ethanol to provide 20–80% inhibition of the blank absorbance, and then the properly diluted samples were added to 3.9 mL ABTS working solutions and mixed thoroughly. The absorbance of reactive mixture was determined at 734 nm after incubation at room temperature (23 ± 1 ◦C) for 6 min. Quantitative results were determined from the standard curve of trolox (0.05–0.8 mM) and were expressed as mmol trolox/g dry weight (DW) extract powder. All tests were performed in triplicate.
