Fatty acid compositions and nutritional value of six walnut (Juglans regia L.) cultivars grown in Iran

Walnuts are good sources of polyunsaturated fatty acids (PUFA) and polyphenols which have beneficial effects such as proper growth, decreasing coronary heart disease, prevention of several kinds of cancer, anti-inflammatory and anti-mutagenic activities. In this study, the fatty acid content and antiradical activity of different walnut (Juglans regia L.) genotypes grown in Kolyaei region located in Kermanshah Province (Iran) were investigated. In this experimental study, fatty acid compositions in different genotypes of Persian walnut were determined using a GC–FID coupled with a flame ionization detector. For antiradical activity, methanolic extracts of different genotypes affected on DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical. BHA (2-tert-butyl-4-methoxyphenol) was used as the reference compound. Total oil content of walnuts ranged from 63.3 to 78.5%. Oleic acid, linoleic acid, linolenic acid, palmitic acid and stearic acid contents ranged respectively from 17.9 to 28.6%, 46.9 to 56.8%, 10.8 to 13.9%, 5.5 to 7.2% and 2.0 to 3.9%, while trace amounts of other fatty acids (<0.1% each) were detected in the samples. The results demonstrated that fatty acid composition is genotype dependent and the highest amounts of PUFA (due to the high content of linoleic acid) were observed in B2 genotype. Among different studied genotypes, the extract of B2 had also the highest radical scavenging activity and therefore the lowest EC50. It was concluded that pellicle is a necessary protecting layer that can help to inhibit the oxidation of fatty acids.