Antioxidant capacity, total phenols and color profile during the storage of selected plants used for infusion

Many plants, like tea, are widely used for preparing herbal infusions. These plants have an interesting antioxidant capacity that may change after harvesting depending on the technological processing and the storage conditions. We determined the antioxidant capacity (ABTS, DPPH and FRAP methods), total phenolic content and color analysis (reflectance) of 36 plants traditionally consumed in Spain as infusion. Green tea was the most antioxidant herb, although oregano and lemon balm showed also a very high antioxidant capacity, as well as phenolic content. The antioxidant study after 3-month storage at different temperatures showed that up to a 50% of the total antioxidant capacity could be lost. Color analysis correlated with antioxidant capacity evolution, being a quick tool to control the storage conditions. Finally, our data confirm that the intake of one serving of plant infusion could release the equivalent of up to 1500 μmol trolox, being a good source of antioxidants for the human diet.