Quality of Canadian Soybean, oilseed-type 2019

5. Fatty acid composition

Table 4 shows fatty acid composition for the combined No. 1 and 2 grade composites from the various provinces. Linolenic acid (C18:2), the main fatty acid found in soybean oil, averaged 55.5% whereas last years average was 53.6%. Oleic acid, the second most important soybean fatty acid, averaged 18.8% in 2019, much lower than the 2018 value of 21.8%. The other important unsaturated fatty acid, ɑ-linolenic acid (C18:3), averaged 9.9% (8.3% in 2018). Total saturates averaged 15.0% in Canada varying from 14.8% (Saskatchewan) to 15.2% (Ontario).

Iodine value estimates the level of fatty acid unsaturation in oil; the higher the number of double bonds in the oil the higher the iodine value and the level of unsaturation. For 2019, both ɑ-linolenic acid and linoleic acid averages were higher than last year; the iodine value average being much higher than last years average, 138.5 units in 2019 versus 133.5 units in 2018, reflects this. Figure 6 presents the iodine value trend since 2006 for eastern Canada and western Canada and the overall Canadian averages. The yearly variations are a reflection of the environmental differences that includes geography (temperature and precipitation being different between eastern and western Canada).

There is no requirement to control the fatty acid composition of the Canadian oilseed-type soybeans; therefore, variety can show large variation in the fatty acid composition. These variations are amplified as weather also plays a part in year-to-year fatty composition changes. In hot and dry weather conditions, seeds tend to produce an oil with more saturation, e.g. less polyunsaturated fatty acids such as linolenic and linoleic acids and more total saturates and oleic acid. The opposite is observed if seeds are grown in cool conditions.