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Change to the calculation and reporting of fatty acid profiles (Flaxseed)

Beginning with the 2007/2008 shipping year there was a change to the manner in which the fatty acid profiles for flaxseed export samples is calculated and reported. Prior to 2007/2008 fatty acid profiles for flaxseed samples were considered to include only the following five major fatty acids found in flaxseed oil: palmitic (C16:0), stearic (C18:0), oleic (C18:1), linoleic (C18:2), and linolenic (C18:3). Fatty acid profiles and Calculated Iodine Values were based on just those 5 major fatty acids, normalized to 100%.

Flaxseed samples contain as much as 0.5% of other minor fatty acids such as arachidic (C20:0), eicosenoic (C20:1), behenic (C22:0), and lignoceric (C24:0). In addition, export composite loading samples, often contain trace amounts of other oilseed crops which can contribute 1% to 1.5% of additional minor fatty acids to the complete profile. As a result, the flaxseed export shipment fatty acid profile can contain any or all of the following fatty acids: myristic (C14:0), palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic (C18:2), linolenic (C18:3), arachidic (C20:0), eicosenoic (C20:1), eicosadienoic (C20:2), behenic (C22:0), erucic (C22:1), docosadienoic (C22:2), lignoceric (C24:0), and nervonic (C24:1). Now they are all included in the fatty acid profile and calculated Iodine Value.

The analysis methods for Fatty Acid Composition (%) and Calculated Iodine Value for the oil extracted from the export sample remains the same: ISO 5508: Animal and vegetable fats and oils-Analysis by gas-chromatography of methyl esters of fatty acids and AOCS Recommended Practice Cd 1c-85: Calculated Iodine Value.

Compared to previous calculations, Iodine Values for export shipments are approximately 2 to 3 IV units lower than were previously reported for an identical export loading sample.

These changes are particularly important to keep in mind as the 2007/2008 crop was also significantly lower in linolenic acid, the major influence on calculated Iodine Value. The lower linolenic acid content of the 2007 flaxseed crop was largely due to the extreme heat experienced in much of the flaxseed growing regions of western Canada. Current harvest survey quality data, including iodine values, is available at : http://grainscanada.gc.ca/Quality/Flax/flaxmenu-e.htm.

D. R. DeClercq
Oilseeds Chemist
Grain Research Laboratory
Canadian Grain Commission