Organic acids
The extraction procedure was previously described by the
authors (Pereira et al., 2013). The equipment was a Shimadzu
20A series UFLC (Shimadzu Corporation, Kyoto, Japan). The chromatographic separation conditions were as follows: Sphere Clone
(Phenomenex, Torrance, CA, USA) reverse phase C18 column (5 m,
250 mm × 4.6 mm i.d.), at 35 ◦C; sulphuric acid (3.6 mM) as mobile
phase at 0.8 mL/min. It was used a photodiode array detector (PDA)at 215 and 245 nm (for ascorbic acid) as preferred wavelengths.
The quantification was performed by comparison of the area of the
peaks recorded at 215 nm with calibration curves of commercial
standards. The results were expressed in g per 100 g of dry weight.