Lipid Composition of Walnut (Juglans regia L.) Cv. Pedro Grown in Bulgaria

Abstract

SUMMARY Lipid composition of walnut ( Juglans regia L.) cv. Pedro grown in Bulgaria (harvest year 2009) has been investigated concerning the neu tral lipid classes, their fatty acid composition and the triacylglycerol species. Fat co ntent of the oil (71.3%) was determined gravimetrically after extraction of dry kernels in Soxhlet apparatus (6 h with hexane). The walnut oil for analyses of lipids was obtained from kernels by a procedure included firstly treatment of walnuts with iso-propanol and then ext raction by chloroform-methanol (2:1) mixture (Christie, 1993). Lipid classes were separa ted by thin layer chromatography (silica gel G plates, developed with hexane-acetone, 10:1 v /v), identified towards a standard mixture, isolated and weighed. The walnut cultivar Pedro was found to contain the following lipid classes: polar lipids (0.5%), diacylglycerols (1.7% ), sterols (0.5%), unidentified lipid zone X (0.7%), triacylglycerols (95.8%) and sterol esters (0.8%). Each of these classes was transmethylated according to Christie (2003) and th e methyl esters were analysed by gas chromatography. The results are given in Tab 1.