Abstract: In this study, the phenolic compounds were analysed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS)，and the antioxidant capacity was evaluated by four evaluation methods in five pickled and dried mustard brands. The results showed that the total phenol contents, the proportion of different phenolic compounds, and their antioxidant capacity were significantly different in five pickled and dried mustard brands. The total phenol content of GGX was 14.18mg GAE/g DW, and the total flavonoid content was 7.10mg RE/g DW, and the antioxidant capacity of ABTS, FRAP, DPPH and ORAC was 28.09, 32.88, 31.72 and 445.55μmol TE/g DW, respectively, all of which was significantly higher than the other four brands of picked and dried mustard. Secondly, 17 kinds of phenolic compounds, including 9 flavonoids and 8 phenolic acids, were identified by HPLC-MS/MS analysis for the first time. Among them, the classes of flavonoids in the pickled and dried mustard are rhoifolin, kaempferol, isorhamnetin, naringenin, etc.; phenolic acids are ferulic acid, p-coumaric acid and t-cinnamic acid, etc. In addition, among the four antioxidant capacity evaluation methods, the correlation between ABTS and FRAP was the highest and the correlation coefficient was 0.967; and the antioxidant capacity of pickled and dried mustard evaluated by the ORAC method was significantly higher than that by the other three methods; the ABTS method had the highest correlation coefficient with antioxidants, which was the most suitable method for evaluation the antioxidant capacity of pickled and dried mustard. In summary, the total phenol content and antioxidant capacity of different kinds of commercially available pickled and dried mustard were different. Among them, GGX had the highest total phenol content and the strongest antioxidant capacity.

Key words: pickled and dried mustard (PDM), phenolic compound, flavonoid, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), antioxidative ability