Characterization of Turkish Quercus L. Taxa based on fatty acid compositions of the acorns

Abstract

Total oil content and the composition of fatty acids were analyzed in the acorns of 16 Quercus taxa from Turkey. The range of total fat varied between 0.7 and 7.4%. Oleic (10.2-54.4%), linoleic (24.2-49.1%), palmitic (13.4-30.4%), alpha linolenic (1.5-8.6%) and stearic acid (1.5-4.5%) were major fatty acids for all taxa. Significantly differences at section level were found (p < 0.05) for palmitic, stearic and oleic acid concentration. Saturated (17.0-38.6%), mono unsaturated (11.0-55.5%) and unsaturated fatty acids (57.4-81.6%) in total oil were also significantly different between section Quercus, Cerris and Ilex (p < 0.05). In addition, sectional differences were significant (p < 0.02) for the relative concentrations of saturated fatty acids compared to mono, poly and total unsaturated fatty acids. Considerable variation of individual fatty acid levels were observed in related species and varieties. The species from section Ilex Loudon exhibited the highest levels of saturated fatty acid while the lowest levels were found in Q. brantii, Q. libani and Q. trojana from section Cerris Loudon. These species also had the highest levels of unsaturated fatty acids. Whereas the lowest values were detected in the species of section Ilex. Both varieties of Q. cerris showed significant differences (p < 0.05) from the other species in section Cerris for all parameters, except for stearic acid and exhibited little variations among their individual populations. Different concentrations of fatty acids may be useful biochemical markers for the characterization of Quercus at the infrageneric level. Interesting ratios of linoleic:alpha-linolenic acid especially in Q. robur ssp. robur, Q. hartwissiana, Q. vulcanica, Q. ithaburensis ssp. macrolepis and Q. libani also were detected with respect to dietary reference for fatty acid intake.