Briefly, carotenoids were extracted with 0.05% (w/v) butylated hydroxytoluene (BHT – 99%, W218405 – Sigma– Aldrich, Milan, Italy) in acetone and 95% ethanol (1:1, v/v), separated by partition into hexane and directly assayed by a Dionex HPLC (Dionex s.r.l., Milan, Italy) with an AD 25 UV–Vis detector