Background and methodology
This study compared the fatty acid composition of commercially available edible oils derived from certified organic and conventional agricultural methods. A total of 59 certified organic and 53 conventional oils were purchased from retail markets in Sydney, Australia. Organic and conventional products were matched for comparison according to the description of production methods, labeled total fat content, brand name, and country of origin. Total fat was extracted and the fatty acid composition of the oils was determined by gas chromatography.
No consistent overall trend of differences in the fatty acid composition was observed between organic and conventional oils. Saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids were all significantly different between types of oil, and each had significant interaction between type and production method, indicating that organic and conventional oils differed in these components in an inconsistent fashion. Despite this, there were large differences particularly between MUFA and PUFA components in specific pairs of oils, especially in sunflower and mustard seed oils. The absence of an overall difference in the fatty acid composition of organic and conventional oils does not support the tenet that organic foods are of a higher nutritional quality than their conventional counterparts.
The approach used in this study is the compositional analysis of products purchased from retail markets. In broad terms, retail market studies differ from farm and cultivation studies in that little or no information is available regarding the specific environmental conditions under which the products were produced, including the time of harvest, variety, ripening, maturation and processing methods. Studies at the retail level are therefore less likely to be representative of the food production system as a whole. A potential disadvantage of obtaining all the samples from retail outlets is the lack of a guarantee of authenticity.
Samman, S., Chow, J. W. Y., Foster, M. J., Ahmad, Z. I., Phuyal, J. L., and Petocz, P. (2008). Fatty acid composition of edible oils derived from certified organic and conventional agricultural methods. Food Chemistry, 109(3), 670-674. Available on-line at: http://dx.doi.org/10.1016/j.foodchem.2007.12.067.