*4.6. Ascorbic Acid Analysis*

The ascorbic acid content was determined using a spectrophotometric method [59]. Fresh plant tissue (1 g) was homogenized in 10 mL of 5% oxalic acid and then centrifuged (5 min, 4000 rpm). The extract (1 mL) was added to 2 mL of 0.1% methyl viologen and 2 mL of 2 mol·L <sup>−</sup><sup>1</sup> NaOH. The colored radical ion was read at 600 nm against the radical blank. The concentration of ascorbic acid was calculated as a function of the values obtained from the <sup>L</sup>-ascorbic acid standard curve (100–500 <sup>µ</sup>g·mL−<sup>1</sup> ) (*R* <sup>2</sup> = 0.9907). Results were expressed as mg·g −1 fresh weight.
