Tocopherol concentration in almond oil: genetic variation and environmental effects under warm conditions.

The concentration of the different tocopherol homologues in almond kernel oil was determined in 17 almond cultivars grown in two different experimental orchards, in Spain and Morocco. The three main homologues showed a large variability, ranging from 210.9 to 553.4 mg/kg of oil for α-tocopherol, from 4.64 to 14.92 mg/kg for γ-tocopherol, and from 0.2 to 1.02 mg/kg for δ-tocopherol. The year effect was significant, independent of the experimental site, for all homologues and total tocopherol, the values of α-tocopherol, γ-tocopherol, and total tocopherol being higher in 2009 than in 2008, whereas the value of δ-tocopherol was higher in 2008. The location effect was also significant, the values of γ- and δ-tocopherol being higher in Spain than in Morocco, whereas for α-tocopherol the location effect was dependent on the genotype. These effects could not be explained by the temperature differences between sites, but probably other undetermined environmental factors might explain the effect of the location, such as rainfall and irrigation supplementation during fruit growing and ripening.