Crop Quality Data, Highlights, and Reports

Quality of Flaxseed in Canada

D.R. DeClercq
Oilseed Chemist, Grain Research Laboratory
Revised April 3, 2007

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 42.0% (dry basis) in the period 1937 to 1960 to over 44.0% (dry basis) in the period 1995 to 2005. Similarly, iodine value has increased from an average of 187 units to an average of 193 units.

However, year-to-year variations in oil content and iodine value can be associated with changes in weather between different growing seasons. The GRL'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 1971, 1989, and in 2003 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 2006 survey are a result of the drier and warmer than normal growing conditions in southern portions of the flaxseed growing area.

Long term trends for oil content and iodine value of Canadian flaxseed

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 flaxseed 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.

Relationship between oil and protein content for No1 CW Flaxseed from 2003 harvest survey samples

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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 2006 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 2006, 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 and Vimy 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 GRL’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 2006 Harvest

Variety1	Province	No. of samples	Oil content2	Protein content3	Iodine value4	Linolenic acid5 (C18:3)
			%	%	units	%
CDC Bethune	Manitoba	72	45.4	24.2	187	54.4
Hanley	Manitoba	26	43.3	24.6	196	58.7
Lightning	Manitoba	7	47.3	23.7	189	55.3
Taurus	Manitoba	22	45.5	24.3	187	54.4
Total/Means	Manitoba	127	45.4	24.2	190	55.7
AC Watson	Saskatchewan	19	44.8	23.7	192	56.6
CDC Arras	Saskatchewan	12	45.3	23.1	190	56.6
CDC Bethune	Saskatchewan	228	46.4	23.2	188	54.6
Taurus	Saskatchewan	10	46.4	22.3	191	56.8
Vimy	Saskatchewan	57	45.9	23.4	192	57.6
Total/Means	Saskatchewan	326	45.7	23.1	191	56.4
CDC Bethune	Alberta	6	46.8	23.1	191	56.1

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

^* Prairie Grain Development Committee, Oilseeds Crops Subcommittee, “Minimum Standards for Linseed Flax Cultivar Registration 2006”, pp. 48 of the Report of Flax Co-operative Test 2006.

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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.

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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).

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For more information on the quality of flaxseed in Canada

Doug DeClercq
Email: ddeclercq@grainscanada.gc.ca

For more information available on this site, select

Flaxseed Export Quality Data
Flaxseed Quality Reports