Effect of Harvesting Time on the Chemical Composition of <i>Cynara cardunculus</i> L. var. <i>altilis</i> Blades

In the present study, the fluctuations in fatty acids, tocopherols, organic acids, and free sugars content of cardoon blades collected at sixteen harvest dates (samples B1–B16, corresponding to principal growth stages (PGS) between 1 and 9) were evaluated. A total of 26 fatty acids were identified, with palmitic (C16:0, 19.9–40.13%), α-linolenic (C18:3n3, 6.39–33.2%), and linoleic (C18:2n6c, 9–34.8%) acids being present in higher relative abundances in most of the samples, while lipid content was the highest in samples of late (B15) and intermediate (B8–B10) stages of maturity. The α- and γ-tocopherols were the only detected vitamin E isoforms, while α-isoform presented the highest concentration (80–8567 µg/100 g dw) in all the studied samples, except for samples B9–B11, for which the γ-tocopherol was detected in higher concentrations. Moreover, samples B1 and B14 showed the highest content of total tocopherols (8352 and 10,197 µg/100 g dw, respectively). The identified organic acids were oxalic, quinic, malic, citric, and fumaric. Malic acid was present in higher concentrations in almost all the samples analyzed, except for samples B3 and B15, in which the presence of oxalic acid stood out. Regarding the free sugar’s composition, fructose, glucose, sucrose, trehalose, and raffinose were the only detected compounds, with sucrose being present in higher concentrations in almost all the samples (1.662–10.8 g/100 g dw), while samples at younger maturation stages, namely samples B4 and B5, presented the highest concentrations of total sugars. In conclusion, the obtained results demonstrate the influence that the growth cycle may have on the chemical composition of this tissue (blades) of the species. Moreover, having a more complete knowledge regarding its composition and identifying the stage of maturation which is most appropriate for obtaining a greater amount of certain bioactive compounds will help to increase the added value of this multi-purpose crop.