Tree Nut Oils: Chemical Characteristics, Oxidation and Antioxidants
Memorial University of Newfoundland (Canada)
, 2005 - Nuts
- 174 pages
The chemical compositions, antioxidant activities and oxidative stabilities of tree nut oils were examined. The oils of almonds, Brazil nuts, hazelnuts, pecans, pine nuts, pistachios and walnuts were extracted using two solvent extraction systems, namely hexane and chloroform/methanol. The chloroform/methanol system resulted in higher oil yield for each tree nut type examined. Pine nuts had the highest oil content while almonds had the lowest. The lipid class compositions of tree nut oils were analysed using thin layer chromatography-flame ionization detection and showed that triacylglycerols were the predominant lipid class present. Smaller amounts of sterols, sterol esters, phospholipids and sphingolipids were also present. The fatty acid compositions of tree nut oils were analysed using gas chromatography, showing that oleic acid is the predominant fatty acid in all samples except pine nut and walnut oils, which contained high amounts of linoleic acid. The sterol and stanol content and compositions were analysed using gas chromatography; beta-sitostanol was the predominant sterol compound present in all samples, with lower amounts of campesterol, stigmasterol, Delta5-avenasterol, 22-nordehydrocholesterol, 24-methylenecholesterol, cholesterol, cholestanol and beta-sitostanol also present. The tocopherol compositions were analysed using high performance liquid chromatography, showing that alpha- and gamma-tocopherols are the predominant tocopherol isomers present; however delta- and beta-tocopherols were also detected in some samples.