MEAL QUALITY CHARACTERISTICS YELLOW MUSTARD (SINAPIS ALBA L.)
Felicitas Katepa-Mupondwa, Gerhard Rakow and Phil Raney
Saskatoon Research Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada, S7N 0X2.
E-mail: Katepaf@em.agr.ca
An important research objective at the Saskatoon Research Centre is the development of high protein content, canola-quality Sinapis alba. Selections have been made among progeny of low erucic acid and low glucosinolate content lines, resulting in plants which are devoid of erucic acid, p-hydroxybenzyl and benzyl glucosinolates. Two cycles of recurrent selection within elite condiment mustard germplasm have resulted in lines with higher mean meal protein content (52.8%, dry weight basis) than the check cultivar AC Pennant (47.64%). Seed size has also been increased. Selected high protein S. alba lines have a mean seed weight of 6.6g/1000 seed, while mean seed weight of AC Pennant is 5.7g/1000 seed. These improvements in fatty acid and glucosinolate profiles, together with increases in protein content and seed weight, represent important milestones in the development of S. alba as a source of high protein supplements.
KEYWORD: erucic acid, glucosinolate, protein supplement.
An important research objective at the Saskatoon Research Centre is the development of high protein content, canola-quality strains of Sinapis alba, to meet the increasing demand for vegetable protein supplements. High protein S. alba will have a dual purpose as a high protein supplement for use in livestock feed formulations and in human processed food products. The oil free meal in S. alba possesses a relatively high protein content (45-48%) (Rakow, personal communication; Josefsson, 1970; Sawar et al., 1981). The amino acid composition of S. alba meal is fairly well balanced (Applequist and Nair, 1977) and similar to Brassica. Compared to soybean, canola and S. alba protein contains less amino lysine, but more of the sulphur amino acids methionine and cystine. Improving meal quality characteristics in S. alba corresponds with research efforts to develop edible oilseed strains of this species. The predominant glucosinolate in S. alba, p-hydroxybenzyl glucosinolate, is present in high concentrations (120-150 mmole/g seed) and gives yellow mustard its characteristic flavor. The high concentration of glucosinolates in S. alba meal has discouraged its use in animal feed formulations or human food applications. The objectives of this research are to improve meal quality characteristics by increasing protein content and reducing p-hydroxybenzyl glucosinolate and erucic acid.
The materials and methodology to develop canola-quality strains of S. alba has been previously described in relation to the development of edible oilseed S. alba (Katepa-Mupondwa et al., 1999; Raney et al., 1995). Protein content was increased through recurrent selection in an elite population of condiment mustard from the yellow mustard breeding program at the Saskatoon Research Centre. The cultivar AC Pennant was developed from the same germplasm base that was used to develop the high protein strains and therefore serves as an appropriate experimental check. Two selection cycles for increased protein were undertaken utilizing large single plant crossing blocks (2500-3000 plants) and evaluation nurseries consisting of replicated half-sib progeny rows pulled from the crossing blocks. In the second cycle of selection, 1092 half-sib progeny lines were evaluated in a 1997 field nursery with two replications. The checks included AC Pennant, Viscount and a bulk pulled from the 1996 crossing block. Reserve seed was utilized for initiating crossing blocks consisting of individuals from lines selected from the half-sib progeny evaluation. During the first cycle of recurrent selection, the breeding population was also selected for increased seed size.
Strains of S. alba which contain no erucic acid, p-hydroxybenzyl and benzyl glucosinolate have been developed (Table 1). The development of canola quality S. alba is an important milestone towards the development of this crop for animal feed and human consumption. Although erucic acid toxicity has not been demonstrated in humans, this acid has been associated with poor performance and abnormal lipid metabolism in heart and skeletal muscle tissue in laboratory animals and pigs (Abdellatif et al., 1970; Holmes, 1980; Laryea et al., 1992). The evidence correlating glucosinolates to poor animal performance as well as to poor human health is strong (Bell, 1977; Bowland et al., 1965; Fenwick et al., 1983). Glucosinolates reduce palatability and feed intake in non-ruminant animals, and inhibit iodine uptake by the thyroid gland, causing goitre and other growth and reproductive anomalies. Canola-quality traits are currently being introgressed into high protein content lines of S. alba.
Two cycles of recurrent selection have resulted in a significant increase in S. alba protein content (Table 2). A selection intensity of 2.3% was applied to select the highest protein content lines from the 1997 nursery. The mean meal protein content of selected lines was 52.8% which was greater than the checks Viscount, the 1996 bulk pull and AC Pennant by 3.0, 3.8 and 5.2%, respectively. The mean protein content of the 1092 lines in the nursery (49.3) was comparable to the mean of the 1996 bulk pull. The difference in mean protein content between AC Pennant and the selected high protein lines was noteworthy and reflects a positive response to selection for increased protein in our experimental material, since AC Pennant had the same germplasm base, but was not selected for protein content.
Response to selection for increased seed weight in the first selection cycle was positive. The mean seed weight of the 1092 lines evaluated in 1997 was 6.2g/1000 seed compared to 5.7g/1000 seed in AC Pennant. Viscount is a small seeded cultivar (5.2g/1000 seed). Selecting for high protein content in the second cycle of selection was correlated with increased seed size. Selected high protein lines had a mean seed weight of 6.6 g/1000 seed. Eleven of the 26 selected lines had seed weights exceeding 7.0g/1000 seed. This result is important because large seeds may be associated with lower fibre content, an important nutritional characteristic. In addition there are agronomic benefits associated with large seeds. These results indicate the potential to increase seed protein content and seed size simultaneously. Oil content decreased as a correlated response to selection for increased protein content.
Relatively little research has been conducted on meal quality characteristics in S. alba, and this research represents important milestones to improving meal quality characteristics. Removing erucic acid, p-hydroxybenzyl and benzyl glucosinolates and increasing seed protein content, enhances the value of this species for use in both animal feed rations and in processed human food products. This research is ongoing with further improvements in the fatty acid and glucosinolate profiles of the seed, and additional increases in protein content and seed weight. As well, other important meal quality characteristics such as fibre are under study.
Table 1. Content of erucic acid, p-hydroxybenzyl and total glucosinolates in Sinapis alba - canola-quality plants and AC Pennant.
|
Sinapis alba |
Erucic acid (%) |
Ho-benzyl glucosinolate |
Total glucosinolates |
|
Canola-Q |
0.1 |
0.0 |
6.3 |
|
AC Pennant |
32.7 |
155.6 |
160.4 |
Table 2. Protein content, seed weight and oil content of Sinapis alba - high protein lines, Viscount, an Experimental bulk pull and AC Pennant
|
Sinapis alba |
Protein (%meal) |
Seed weight (g/1000 seed) |
Oil (% seed) |
|
High protein |
52.8 |
6.6 |
26.1 |
|
Viscount |
49.8 |
5.2 |
27.3 |
|
96BulkPull |
49.0 |
6.0 |
27.2 |
|
AC Pennant |
47.6 |
5.7 |
28.3 |
Strategic support for this project has been provided by the Canada-Saskatchewan Agri-Food Innovation Fund. Mr. Todd Olson, Mr. Don Rode and Ms Jo-Anne Relf-Eckstein are gratefully acknowledged for their technical assistance.
Abdellatif. A. M. M., and R. O. Vless. 1970. Physical effects of rapeseed oil and canola oil in rats. P. 423-432. In Proceedings of the International Conference on Rapeseed and rapeseed products St. Adele, Canada.
Applequist, L. A., and B. M. Nair. 1977. Amino acid composition of some Swedish cultivars of Brassica species and of Sinapis alba. Can. J. Anim. Sci. 73:679-697.
Bell, J. M. 1977. Proceedings of the symposium on rapeseed oil and meal: Production and Utilization. Rapeseed Association of Canada, Publication #45:137-194
Bowland, J.P., D. R. Clandinin, and L. R. Wetter. 1965. Rapeseed meal for livestock and poultry-a review. Agriculture and Agri-food Canada, Publication #1257.
Fenwick, G. R. , R. K. Heaney, and W. J. Mullin. 1983. Glucosinolates and their breakdown products in food and food plants. CRC Critical Rev. Food Nutrition. 18:123-201.
Holmes, M. R. J. 1980. Nutrition of the oilseed rape crop. Applied Sci. Publishers Ltd., London.
Josefsson, E. 1972. Nutritional value and use of rapeseed meal. In Rapeseed: Cultivation, Composition, Processing and Utilization. Eds: Applequist, L.A. and Olson. Elsevier publ. Comp. NY. P354-378.
Katepa-Mupondwa, F., G. Rakow, P. Raney, and R. Gugel, 1999. Sinapis alba: A new oilseed crop for the prairies. Soils and Crops Conference Proceedings. University of Saskatchewan. In Press.
Laryea, M.D. Y. F. Jiang, G. L. Xu, and I. Lombeck. 1992. Fatty acid composition of blood lipids in Chinese children consuming high erucic acid rapeseed oil. Ann. Nutr. Metab.36(5/6): 273-278
Raney P., G. Rakow, and T. Olson. 1995. Development of Low Erucic, Low Glucosinolate Sinapis alba. Proc. 9th Int. Rapeseed Cong., Cambridge, UK. Vol2: 416-418.
Sarwar, G., J. M. Bell, T. F. Sharby and J. D. Jones. 1981. Nutritional evaluation of meal fractions derived from rape and mustard seed. Can. J. Animal Sci. 61: 719-733.