2.7. Determina tion of ascorbic acid
The content of ascorbic acid was measured according to the
method reported by Lee and Coates [10] with slight modifications
by an Agilent 1100 series HPLC (AgilentTechnolo gies, USA)con-
sisted of amodel G1379A degasser,amodel G1311A pump,amod-
el G1316A column oven and model G1315B diode array detector
(DAD). The column used was Tskgel ODS-100Z column
(4.6 150 mm, 5 lm, Tosoh,Japan).The mobile phase was 30%
(v/v) methanol in distilled water with aflowrate of 1.0 mL/min.
The detector was set at 280 nm.Before analysis,the juice was fil-
tered by using 0.45 lm diameter syringe filter,and the injection
volume was 20 lL. Asuitable calibration curve was prepared using
standard solution of ascorbic acid and the results were expresse d
as mg/100 mL of apple juice.