The ascorbic acid content in pear juice was determined as described by Lee and Coates (1999) with some modifications. An Agilent 1100 series HPLC (Agilent Technologies, Santa Clara, CA, USA) with the main components of a G1379A model degasser, a G1311A model pump, a G1316A model column oven and a G1315B model diode array detector (DAD) was used. Before injection,0.45 mm syringe filters were used to filter the samples and 20 mL of the filtered sample was injected into the system. Tskgel ODS100Z C18 column (4.6 mm 150 cm, 5 mm, Tosoh Co. Inc., Tokyo, Japan) was used, and the mobile phase was aqueous methanol solution (30 mL/100 mL) at a flow rate of 1.0 mL/min. Standard ascorbic acid solutions were used to set up the calibration curve and the results were expressed as mg/100 mL
of pear juice.