2.3.5. Measurement of ascorbic acid
The ascorbic acid (AA) present within the sample was extracted in
2% metaphosphoric acid solution in double distilled water. AA content
was measured by the direct colorimetric method based on its ability
to decolorize 2,6-dichlorophenol-indophenol dye solution as described
by Ranganna (2007). Interference was avoided by rapid determination
and the corresponding AA content was obtained from a standard
curve drawn for pure L-ascorbic acid (Sigma-Aldrich) solution which
varied within 0.2 to 1 g·L−1 of AA. The relative loss in AA content
(in %) of treated sample was calculated with respect to the untreated
sample.