Flaxseed quality in Canada

Canadian flax quality shows long term consistency and improvement

Canadian flaxseed is valued for its consistent high quality. This quality is measured as high oil content, high iodine value and low moisture, admixture and free fatty acids. Measurements over the past 70 years show that oil content has increased from an average of 43.5% (dry basis) for the ten-year period 1937 to 1946 to 44.7% (dry basis) in the period 1997 to 2006. Iodine value has increased from an average of 192 units in the ten -year period 1975 to 1984 to an average of 193 units for the ten-year period 1995 to 2004.

However, year-to-year variations in oil content and iodine value can be associated with changes in weather between different growing seasons.  The Grain Research Laboratory’s long-term harvest survey results have shown that hot, dry growing conditions tend to produce a flaxseed crop with lower oil contents and iodine values, but higher protein contents.  For example, extreme drought and heat stress in  1989, 2003 and 2007 resulted in decreased oil contents and iodine values for those crop years. In contrast, the 2004 season was among the coolest reported in over 100 years, resulting in a record high iodine value of 201 units. In 2005, the month of June 2005 is tied with June 1953 for the wettest month on record for Saskatchewan in the last 90 years, contributing to a record high western Canada flaxseed oil content of 46.2% in the 2005 survey samples.  The decreased oil contents and iodine values seen in the 2007 survey are a result of the drier and warmer than normal growing conditions in much of the southern portions of the flaxseed growing area.

Year-to-year variations in oil content and iodine value in flaxseed harvest and exports between 1940 and 2000.

The average quality of exported seed closely follows the average quality of harvested seed although in some years, large carryover stocks of seed from previous harvests have a leveling effect on the quality of exported seed. It should be noted that there is a strong inverse relationship between oil contents and protein contents for whole flaxsseed samples. In general, those samples that have lower seed oil contents will likely produce a seed with a higher protein content, which may be of benefit for the flaxseed meal industry. The typical relationship between oil and protein content for whole flaxseed samples is shown with the 2003 harvest survey results.

This scatter plot shows the relationship between oil content and protein content in No. 1 Canadian Western flaxseed.  These results are based on 2003 harvest survey samples.

Key to Canadian flax quality is in the Canadian varietal development system

The primary reason for the high quality of Canadian flaxseed is the active involvement of plant breeders in maintaining and increasing quality standards. The current guidelines for registration of flaxseed cultivars in Canada state that oil content, iodine value and protein content of new cultivars may not be significantly less than the variety Flanders^*.

In a survey of varieties of flaxseed grown in 2007 in western Canada, samples of CDC Bethune and Taurus had the highest mean oil contents of the varieties received from Saskatchewan. For Manitoba samples, Lightning had the highest mean oil content. In 2007, a year when the flaxseed crop was grown under much drier and warmer conditions than the previous year, the Hanley samples from Manitoba and the AC Watson, the CDC Sorrel, and the Taurus samples from Saskatchewan, had the higher mean iodine values. The use of Flanders as the quality check sample for the variety registration trials has contributed to the improved quality of newer flaxseed cultivars. The previous quality check cultivar, Norlin, was typically among the lowest for oil content.

The Grain Research Laboratory’s long-term harvest survey results have shown that cool growing conditions tend to produce a flaxseed crop with higher oil contents and iodine values, but lower protein contents. While environmental stress such as heat or drought will generally lower oil contents and iodine values, not all cultivars respond to the same degree.

Quality of flaxseed varieties from 2007 harvest

Variety1	Province	No. of samples	Oil content2, %	Protein content3, %	Iodine value4, units	Linolenic acid5 (C18:3), %
CDC Bethune	MB	46	44.5	23.7	181	51.4
Hanley	MB	14	44.0	23.1	188	54.4
Norlin	MB	7	43.7	23.9	182	52.3
Taurus	MB	11	44.3	24.3	178	49.9
Total/Means	MB	78	44.1	23.8	182	52.0
AC Watson	SK	13	44.6	24.1	187	54.0
CDC Arras	SK	11	46.6	22.5	186	54.7
CDC Bethune	SK	137	45.4	24.4	181	51.0
CDC Sorrel	SK	5	45.6	24.2	187	55.2
Taurus	SK	10	46.2	23.2	187	54.7
Vimy	SK	39	44.7	24.7	181	51.8
Total/Means	SK	215	45.5	23.8	185	53.6
CDC Bethune	AB	3	44.3	25.7	181	51.0

¹ as indicated on submitted survey envelopes
² moisture-free basis
³ % N (nitrogen) x 6.25; moisture-free basis
⁴ calculated from fatty acid composition
⁵ % of Linolenic Acid (C18:3) in the oil

^*1 Prairie Recommending Committee for Oilseeds, “Minimum Standards for Linseed Flax Cultivar Registration 2007”,  pp. 47 of the Report of Flax Co-operative Test 2007

Canadian grade standards and handling system ensure that flax quality is uniform

In the Canadian grain handling system, farm deliveries from many different locations are merged, first at the country elevator and then at export terminal elevators. This process results in a general averaging of the quality of Canadian flaxseed. There is a large reduction in the range between high and low values for oil and protein content between farm-delivered samples and export shipments.

Range in values

	Farm deliveries	Export shipments
Oil (%)	9.6	2.3
Protein (%)	10.0	2.6
Iodine value	20	6

Effects of grade on flax quality^**

Grade	Oil content	Protein content
No. 1 Canada	44.0	23.5
No. 2 Canada	43.0	22.7
No. 3 Canada	41.3	22.4

^** Daun, J.K. Oilseeds Processing Chapter D11 in Grains and Oilseeds, Handling, Marketing, Processing, Vol 11. Canadian International Grains Institute, Winnipeg, Fourth Edition, 1993. p. 891.

Canada's visual grading system also helps to ensure uniform quality of flaxseed. Flaxseed is graded based on the damage (mainly broken seeds) and admixture, first at receipt at the country elevator and again on entering and leaving terminal elevators. This allows low quality seed to be segregated resulting in a more uniform export product. Oil and protein content are lower in lower quality flaxseed.

Canadian climate promotes high oil and iodine value with low moisture and free fatty acid (FFA)

Flaxseed in Western Canada is planted in May or early June and harvested in September or October. This period corresponds to the Canadian summer and early fall seasons. High oil content and iodine value in flaxseed are influenced by lower growing temperatures and by longer photoperiod***. The relatively long day length at Western Canada's high latitudes (49N to 53N) coupled with relatively cool summer temperatures (17 for summer) combine to give Canadian flaxseed a good combination of oil and iodine value.

In comparison, flaxseed grown in the Northern United States is grown between 42N and 49N under somewhat warmer temperatures (20°C) while flaxseed in Argentina is grown between 32S and 38S with a mean temperature of (23.6°C).

In addition, Canadian flaxseed is harvested in the fall, traditionally a dry period in the Canadian prairies. The seed usually requires no drying and is binned with moisture contents usually about 8% and this value is also typical for exported moisture contents. The low moisture at harvest also means that top grade Canadian flaxseed typically has low levels of free fatty acids, usually about 0.6% expressed as % of the oil.

*** Sosulski, F.W. and Gore, R.F. The Effect of Photoperiod and Temperature on the Characteristics of Flaxseed Oil. Canadian Journal of Plant Science 44:382 (1964).