Total antioxidant capacity assay kit with abts method

Approximately 2.0 g of citrus peels from each sample were freeze‐dried using a vacuum freeze dryer and then ground into powder using a mortar. The antioxidant activities of citrus peels were evaluated by the DPPH radical scavenging activity assay. Briefly, 0.02 g of citrus peels was mixed with 180 µl of a DPPH working solution. The mixture was incubated at room temperature for 30 min in darkness. The absorbance was measured at 517 nm with a microplate reader (Sirivibulkovit et al., 2018). The ABTS radical scavenging capacities of citrus peels were conducted with a Total Antioxidant Capacity Assay Kit with ABTS method (Beyotime Biotechnology Co., Ltd.). Trolox was used as a standard compound. A calibration curve was prepared with different concentrations of Trolox in solution, and the results were expressed as mmol TEAC/L of citrus peels where TEAC is defined as the Trolox equivalent antioxidant capacity (Polak & Bartoszik, 2018). The reducing abilities of citrus peels were measured by a Total Antioxidant Capacity Assay Kit with the FRAP method (Beyotime Biotechnology Co., Ltd., Shanghai, China). The standard curve was constructed using FeSO4 solution, and the results were expressed as l M Fe(II)/g dry weight of the citrus peels (Mozaffari et al., 2018).

The antioxidant activity was assayed using a Total Antioxidant Capacity Assay Kit with ABTS method (Beyotime Biotechnology). Briefly, the fresh ABTS working solution was prepared by mixing ABTS stock solution with oxidant solution for an overnight reaction, and then this mixture was diluted 50 times by 80% ethanol. To initiate the assay reaction, 10 µL of each sample with a concentration of 1.0 mM in 80% ethanol was mixed with 200 µL of fresh ABTS working solution. After being incubated at 30 °C for 5 min, the 734 nm absorbance was measured on a Thermo Varioskan LUX Microplate reader. Trolox was used as the reference compound for calculation of ABTS-reducing activity (in %).