2.2.7. Simultaneous Analysis of Organic Acids and Sugars

All samples were thawed and then the juice from each sample was filtered with a C18 Sep-Pak cartridge (Grace Pure TM, New York, NY, USA) and then with a 0.2 μm filter. After dilution (1:1) with ultrapure water, 10 μL-samples were injected into an HPLC system (Agilent 1200 series) equipped with an UV detector, set at 210 nm, and a refractive index detector. Compounds were separated on a Rezex ROA-Organic Acid H + (8%) column (300 × 7.80 mm) (Phenomenex, Torrance, CA, USA), using an aqueous mobile phase of 0.1% phosphoric acid, (flow rate of 0.5 mL·min<sup>−</sup>1) and an oven temperature of 30 ◦C. The different organic acids and sugars were quantified by chromatographic comparison with analytical standards. Resulted were expressed as g·kg<sup>−</sup>1.
