CANOLA-QUALITY BRassica juncea, A NEW OILSEED CROP FOR THE CANADIAN PRAIRIES
Derek A. Potts1, Gerhard W. Rakow2 and Daryl R. Males1
1Saskatchewan Wheat Pool, Research and Development, 201-407 Downey Road, Saskatoon, Saskatchewan, Canada, S7N 4L8, derek.potts@swp.com, daryl.males@swp.com, 2Agriculture and Agri-Food Canada, Research Station, 107 Science Place, Saskatoon, Saskatchewan, Canada, S7N 0X2, rakowg@em.agr.ca
Brassica juncea is considered to have superior adaptation to the semi-arid conditions of the Canadian prairies compared with the current canola species, B. napus and B. rapa. Researchers have worked towards the development of canola-quality B. juncea since the early 1980’s. Previous work resulted in lines that had zero erucic acid and low glucosinolate content, but were low in oil and oleic acid content. Brassica juncea varieties have now been developed that meet the requirements of the canola industry. Field experiments demonstrate that these varieties perform well in comparison with current canola. Test crush results indicate that the oil derived from these varieties has all of the essential characteristics of canola oil. Animal feeding studies have shown that the meal is equal or superior to canola meal. Regulatory issues must be resolved before full commercialization can occur.
KEYWORDS: Oil quality, fatty acid profile
Brassica juncea (L.) Czern. is currently grown in western Canada to produce condiment mustard and is considered to be better adapted to the hot, dry conditions of the southern prairies than the currently grown canola species, B. napus and B. rapa (Woods et al., 1991). Since the first low erucic lines of Brassica juncea were discovered in Australia (Kirk and Oram, 1981), researchers have been working towards the development of canola-quality B. juncea (CQJ). Workers at Agriculture and Agri-Food Canada (AAFC) developed a low glucosinolate strain of B. juncea through an inter-specific cross with B. rapa (Love et al., 1990). The first low glucosinolate lines had poor fertility, high erucic acid content and low oil content. In 1991, Saskatchewan Wheat Pool joined with AAFC to develop and commercialize CQJ. Improved lines were created by crossing to lines with high oil and good yield potential (Rakow et al., 1995).
Meal from low glucosinolate, low erucic B. juncea has been tested in feeding studies with pigs (Bell et al., 1998) and broilers (Newkirk et al., 1997) and has been found to be equal or better in feeding value than canola meal in animal diets.
The fatty acid profile of zero erucic lines of B. juncea was more unsaturated than canola cultivars of B. napus or B. rapa. The oleic acid content of the zero erucic lines of B. juncea was about 15% less and the linoleic acid about 15% higher than that of B. napus. This was considered undesirable because of the poor stability of unsaturated oil and would have prevented the use of B. juncea oil as canola. Efforts were made to change the fatty acid profile through interspecific crossing (Agnihotri et al., 1995; Raney et al., 1995), mutagenesis and genetic engineering.
This paper discusses the development of B. juncea lines that produce oil that is essentially the same as canola oil.
Crosses were made between two breeding populations of canola-quality B. juncea. These populations (designated P and R), have been described by Love et al. (1991). Lines derived from one of these crosses were found to have fatty acid profiles similar to B. napus cultivars. Unfortunately, these lines all contained 2-propenyl (allyl) glucosinolate and therefore were not acceptable as CQJ. Crosses were made between lines with the modified fatty acid profile and lines containing very low levels (< 1 µmole per gram whole seed) of allyl glucosinolate. Microspore-derived doubled-haploid (DH) plants were produced and selected for a combination of high oleic acid (> 55%) and low allyl glucosinolate content. Selection was also carried out for agronomic performance, high oil content and high protein. Lines with acceptable quality were grown in four-replicate yield trials in southern Saskatchewan and Alberta at seven locations in 1997 and 10 locations in 1998. Two lines were selected for seed increase in 1998. Seed from one seed increase plot was used for a pilot plant test crush in 1998. The seed (775 kg) was tempered, flaked, cooked, pressed and solvent extracted. The resulting crude oil was acid degummed, refined, bleached and deodorized.
The results of multi-location yield trials conducted over two years are summarized in Table 1. The checks used in these trials were the B. napus and B. rapa checks currently used for variety registration in western Canada. Usually there is a larger difference in yield between B. napus and B. rapa than is shown in Table 1. Under semi-arid conditions, B. rapa sometimes performs relatively well in comparison to B. napus. The early maturity of B. rapa means that it can sometimes mature before hot, dry weather occurs. B. juncea line J90-4316, previously described by Rakow et al. (1995) was also used as a check. It has good agronomic performance, but has a low oleic content and lower than desired oil content. PC97-32 is an example of a canola-quality line that has an acceptable fatty acid profile and very low allyl glucosinolate content. PC97-32 has good yield and acceptable maturity in comparison to the current canola checks. PC97-32 and other CQJ lines are usually tall, but generally have acceptable lodging resistance. As expected, the blackleg resistance of the B. juncea lines is very good. Oil content is usually 1.0 to 1.5% lower than B. napus and therefore raising the oil content remains a major breeding objective. Brassica juncea lines with high oil content are available and are being used to increase oil content in CQJ.
The B. juncea oil produced from the test crush met the essential specifications for canola oil as determined by Food Chemicals Codex (1996) (Table 2). The oil has a desirable fatty acid profile, very similar to that of B. napus, and has very good stability. The meal is low in glucosinolate content, particularly the allyl form. For registration of CQJ in Canada, the allyl glucosinolate limit has been set at one µmole per gram of seed.
Table 1. Performance of selected Brassica juncea lines and canola checks grown in western Canada at 7 locations in 1997 and 10 locations in 1998.
|
|
Yield (% cks) |
Maturity (days) |
Height (cm) |
Lodge (1-5) |
Oil (%) |
Protein (%) |
c-18:1 (%) |
Blackleg (%Westar) |
|
B. napus1 |
103.4 |
85.6 |
116 |
1.4 |
46.0 |
45.1 |
63.6 |
60.0 |
|
B. rapa2 |
96.6 |
75.8 |
105 |
1.8 |
46.4 |
42.5 |
59.7 |
73.9 |
|
J90-4316 |
120.4 |
84.6 |
141 |
2.1 |
43.2 |
42.6 |
45.4 |
35.5 |
|
PC97-32 |
109.9 |
86.5 |
143 |
1.6 |
44.6 |
45.2 |
65.2 |
29.3 |
1 Values are the means of the three B. napus check cultivars; AC Excel, Defender and Legacy.
2 Values are the means of the three B. rapa check cultivars; AC Parkland, Maverick and Reward.
Table 2. Quality characteristics of refined, bleached, deodorized oil obtained from pilot plant test crush of canola-quality Brassica juncea.
|
Property |
FCC standard1 |
Brassica juncea |
|
Free fatty acids (%) |
Ł 0.05 |
0.02 |
|
Iodine value |
110 – 126 |
110.5 |
|
AOM (hours) |
ł 7 |
22.0 |
|
c-16:0 (%) |
< 6.0 |
3.9 |
|
c-18:0 (%) |
< 2.5 |
2.6 |
|
c-18:1 (%) |
> 50.0 |
62.7 |
|
c-18:2 (%) |
< 40.0 |
17.2 |
|
c-18:3 (%) |
< 14.0 |
9.5 |
|
c-22:1 (%) |
< 2.0 |
0.2 |
|
Glucosinolates (µmoles/gram oil-free meal) |
|
|
|
Allyl |
|
0.4 |
|
Total |
|
11.4 |
1 Food Chemicals Codex (1996) specifications for canola oil.
Brassica juncea lines with canola quality characteristics and with good adaptation to the semi-arid regions of western Canada have been produced. The requirement for a fatty acid profile similar to B. napus was the last major scientific hurdle, and this has been overcome. B. juncea will have to be accepted in domestic and major international markets as a canola species before full commercialization can occur. For example, the Seeds Act of Canada does not currently list B. juncea as a species that produces canola. Until the regulations and seed grade tables are changed, crushers and exporters are unable to accept B. juncea as canola. Canola-quality B. juncea is considered to be a “novel food” in Canada and therefore Health Canada will have to approve the product for food use. Substantial equivalence of CQJ and current canola oil must be demonstrated. Likewise, the Food and Drug Administration of the US will have to accept CQJ as generally regarded as safe (GRAS) before the oil can be labeled as canola in the US.
The use of the term “canola-quality mustard” will be problematic for food labeling and international trade. For this reason, there is an effort being made to have B. juncea accepted as a type of rapeseed, as well as a type of mustard. This will allow CQJ to be traded as low erucic acid rapeseed in countries that do not recognize the term "canola”.
Now that B. juncea that is truly canola-quality has been produced and tested, the regulatory issues are being addressed. The third species of canola, under development since 1981, should soon be a reality.
Agnihotri, A., Kaushik, N., Singh, N.K., Raney, J.P. and Downey, R.K. 1995. Selection for better agronomical and nutritional characteristics in Indian rapeseed-mustard. Proc. 9th Int. Rapeseed Cong., Cambridge, U.K. pp. 425-427.
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