Characterizing of Oil Quality and Fatty Acid Profiles of Old Olive Trees in Palestine.

Abstract

Olive growing in Palestine plays an important role at social and economic levels. Nevertheless, the quality of olive oil produced in the country has not been fully addressed. This study examined oil content, peroxide values, acid values, fatty acid profile, and total phenolic content for old olive trees located in different climatic regions in Palestine during the years 2008-2010. Oil content was determined using both Soxhlet and Abencor systems. Acid and peroxide values were determined using standard methods. Total phenolic content was determined using the Folin-spectrophotometric method. Gas chromatography was used to analyze the main fatty acids found in olive oil e.g., palmitic, palmitoleic, stearic, oleic, linoleic. Different ratios indicating olive oil quality were also determined e.g., sum ratio of unsaturated fatty acids to the sum of saturated fatty acids; ratio between the sum of monounsaturated fatty acids to the sum of polyunsaturated fatty acids, and the ratio between the oleic to linoleic fatty acids. Significant differences were found between geographic regions for the overall studied oil parameters. Wide variation ranges were obtained for fatty acids in the different West Bank locations in the three years. The major fatty acids in the olive oil samples were found to be oleic, palmitic, stearic, linoleic, and palmitoleic acids. The oil samples were found to contain more oleic acid and less linoleic and linolenic acids that is, more monounsaturated than polyunsaturated fatty acids. Total phenolic content was found to range from 125.0-978.0, 207.4-763.8, and 103.0-747.6 mg/kg in 2008, 2009, and 2010, respectively. The acidity percentage was in the range of 0.10%-1.05%, 0.11%-1.29%, and 0.10%-1.91% in 2008, 2009, and 2010, respectively. Peroxide values ranged from 2.26-13.1, 2.94-14.95, and 2.49-17.21 in 2008, 2009, and 2010, respectively.