Total ascorbic acid content was determined in accordance with
the method previously described by and modified by Separation and detection of L-ascorbic acid (AA)
was performed on an Agilent 1100 series HPLCsystem (Agilent Technologies,
Waldbronn, Germany) with a monolithic Chromolith Performance
RP-18e column fitted with a Chromolith RP-18e guard
cartridge, both obtained from Merck KGaH (Darmstadt, Germany).
AA was detected at 264 nm and quantified by external standard. Total
ascorbic acid is the sum of AA and dehydroascorbic acid (DHAA)
in the samples and was determined after reduction of existingDHAA
to AA. The content of total ascorbic acid was expressed as mg AA per
100 g FW. The samples were analysed in duplicates.