Characterization of Walnut Oils (Juglans regia L.) from Asturias, Spain

A total of 15 walnut (Juglans regia L.) samples from 15 cultivars from different geographical areas (Villaviciosa, Colunga, Ribadesella, Llanes, Nava, Peñamellera and Sariego) from Asturias, Spain were studied. Samples of virgin walnut oil were obtained from dehusked ground walnuts by extraction at a pressure of 160 kg cm−2 and temperature below 40 °C for 3 min. The oil obtained by pressure was filtered for analysis. Fatty acid, sterol and tocopherol compositions as determined by capillary column gas chromatography (GC) and triacylglycerols composition as determined by high performance liquid chromatography (HPLC) are reported. The overall composition (percentages of husk, oil and moisture) was also determined. The higher percentages of fatty acids, as determined by capillary GC, corresponded to palmitic (6.11 ± 0.06–7.49 ± 0.04%), oleic (11.70 ± 1.10–18.90 ± 1.19%), linoleic (59.81 ± 1.03–64.77 ± 1.25%) and linolenic (11.11 ± 0.05–15.65 ± 1.09%). γ‐Tocopherol was the major component of the total tocopherols in the sample under study (289.01 ± 6.02–676.52 ± 5.98 mg kg−1 oil). β‐Sitosterol was the major sterol found (78.61 ± 1.45–86.50 ± 1.35%) followed by Δ5‐avenasterol (5.54 ± 0.92–13.81 ± 1.06%). The main triacylglycerides were LLL (24.67 ± 1.31–29.20 ± 1.22%), followed by LLLn (14.63 ± 1.01–17.06 ± 1.13%), OLL + PoLO (13.81 ± 1.01–16.14 ± 1.16%) and PLL + LnOO (11.83 ± 1.09–14.10 ± 1.10%).