*6.1. Tocopherols (Vitamin E)*

Tocopherols, or vitamin E, are a group of soluble compounds that includes four tocopherols (designated as α, β, γ and δ) and four tocotrienols (designated as α, β, γ, y and δ) [80]. Tocopherols are natural mono-phenolic components with di fferent antioxidant activity, which have several homologues depending on the position and number of methyl radicals. Their main biochemical function is probably the protection of polyunsaturated fatty acids against peroxidation. A good number of scientific studies focused, in the first instance, on the tocopherol content and its e ffect on the maintenance of oil properties. Almond kernel is considered one of the richest foods in α-tocopherol [82,83].

Tocopherol content in almonds shows a wide range of variability, as summarized in Table 3. The form with higher concentration in almond kernel oil is α-tocopherol. Variability depends on almond genotypes (cultivars), climatic conditions and environmental conditions. Kodad et al. [10], in a study about 44 Spanish cultivars, for two consecutive years, found a large variability in tocopherol concentrations, in almond oil, with a significant e ffect of both the genotype, the year and the interaction genotype × year. The main source of variability appeared due to the genotype. The geographical origin was significant with higher concentrations of tocopherols in almond populations with a mountainous origin, probably due to the empiric selection to increase the shelf life, since tocopherol retards the rancidity appearance. Abiotic stress leads to higher tocopherol contents due to its protective role. Similar conclusions reached Zhu [28], after analyzing samples of cultivars from Australia, Spain and the United States, and Yada et al. [9], with Californian cultivars from di fferent regions. Besides, as the trees matured from one year to the next, the vitamin E concentration increased [10]. The obtained results also show that the homologues α and δ are those that present higher variability. Higher concentrations found by Maestri et al. [30] in the Argentine Northeast, where the kernel development matches mainly with spring and summer, with medium temperatures that are warmer to those typically observed in the Mediterranean region, can explain these values.



**Table 3.** *Cont.*
