The analysis of ascorbic acid was performed following the method of Giménez et al. (2002) with slight modifications. Portions of 25 mg of dehydrated sample were mixed with 2.5 ml of a 10% (w/v) metaphosphoric acid solution, and then diluted to a final volume of 25 ml in an amber glass volumetric flask with bi-distilled de-ionised water. The sample was centrifuged at 16,500 g/15 min.