An aliquot of 20 μL of extract was injected into the HPLC system
using a reverse-phase C18 Spherisorb ODS2 (5 μm) stainless-steel column
(4.6 mm × 250 cm). The mobile phase was a 0.01% sulfuric acid solution
adjusted to pH = 2.6. The flow rate was 1 mL/min at room
temperature. Detection was performed with a 486 Absorbance Detector
(Waters, Milford, MA) set at 245 nm. Identification of the ascorbic acid
was carried out comparing the retention time and UV–visible absorption
spectrum of the juice samples with those of the standards (ascorbic