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

Abstract

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%). c-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). b-Sitosterol was the major sterol found (78.61 ± 1.45-86.50 ± 1.35%) followed by D 5 -avenasterol (5.54 ± 0.92-13.81 ± 1.06%). The main triacylglycerides were LLL (24.67 ± 1.31-29.

Genotype and year variability of the chemical composition of walnut oil of Moroccan seedlings from the high Atlas Mountains

“…The mean value over the two years ranged between 188.1 and 230.7 mg·kg −1 oil for γ-tocopherol (Table 3). This range agreed with previous results (Amaral et al, 2005), but the maximum values of the Moroccan seedlings were lower than those previously reported (Savage et al, 1999;Bada et al, 2010). The concentration of δ-tocopherol ranged from 23.3 to 43.4 mg·kg −1 oil (Table 3), higher than in a previous report (Amaral et al, 2005), but lower than in others (Savage et al, 1999;Bada et al, 2010).…”

“…Oil content ranged between 54.4 and 67.48%, and protein between 11.58 and 14.5% in 2009, (Table 1), whereas in 2010 these ranges were between 55.29 and 66.25% for oil, and between 11.99% and 14% for protein (Table 1). Protein content agreed with previous reports (Amaral et al, 2003;Savage et al, 1999), as well as fat content, although the lowest fat value was lower than any previous report (Crews et al, 2005;Amaral et al, 2003;Martinez et al, 2006;Bada et al, 2010). The significance of the year×genotype interaction (Table 2) indicated that oil content variability was significant between years for some genotypes, as a result of the specific response by these genotypes to the environmental conditions of the year.…”

“…The ranges of variability for the main FAs, as shown in Table 1, were different for the two years, but similar to those already reported in other walnut oils (Amaral et al, 2003;Martinez et al, 2006;Savage et al, 1999;Bada et al, 2010). The highest values of the walnut oil were found for PUFAs: the FAs were reported as the most effective in reducing low-density-lipoprotein cholesterol in humans, although high linoleic and linolenic acid contents may result in a poor oxidative stability and shorter shelf-life of the oils (Abbey et al, 1994).…”

“…The tocopherol profile showed that γ-tocopherol was the major homologue, followed by α-and δ-tocopherol (Table 3), as in other genotypes (Amaral et al, 2005;Bada et al, 2010). The three tocopherol homologues showed high variability among the genotypes (Table 4), as already observed in nine cultivars, where tocopherol content was also affected by environmental factors (Amaral et al, 2005), although few significant differences were observed for the individual tocopherol homologues in the other three cultivars, where the crop year was the main variability source (Martinez et al, 2006).…”

“…The year effect had been significant for all fatty acids, except for stearic and linoleic acids, in an Argentinian study (Martinez et al, 2006). The variability in the FA composition has been well studied in walnuts (Amaral et al, 2003;Martinez et al, 2006;Bada et al, 2010), concluding that this composition depended primarily on the genotype, with significant effects of the year, the environment, the geographical origin, and agricultural practices. In our study, the highest contents of linoleic and linolenic acids were obtained in 2009 and, conversely, that of oleic acid in 2010 (Table 1).…”