Moreover, the antioxidant activity of orange peel increases with the increase of pressure from 7.941 ± 0.051 M at 0.1 MPa to 11.911 ± 0.151 M at 100 MPa. These results can be explained by the formation of degradation products with antioxidant properties due to high pressure; these products may be provided from Maillard reactions or enzymatic oxidation (Schwartz et al., 2003).