Quality of the 2017 spring canola harvested in western Canada

The 2016 harvest period stretched from August 2016 to May (June) 2017. This extended harvest period was due to adverse weather conditions; rain and snow during the fall of 2016. It is difficult to estimate how much production of canola was affected and its impact on the quantity of canola harvested during the 2017 spring. However, using Statistics Canada data the non-harvested canola hectares could be estimated for each province (Table 1).


Table 1: Summary statistics and sample results (Samples analyzed up to January 20, 2017)
Seeded area (hectares) Harvested area (hectares) % area non-harvested in 2016 Production (MT)
Manitoba 1,276,800 1,256,500 1.6 2,744,200
Saskatchewan 4,492,000 4,224,900 5.9 9,752,200
Alberta 2,407,900 2,225,800 7.6 5,783,300
British Columbia 38,400 34,800 9.4 81,600
Statistics Canada

This report is based on the 173 samples of spring canola that were received. Up to June 20th, 2017, only 161 were analyzed as twelve canola seed samples were not analyzed because they were extremely moldy when they arrived in the laboratory. At harvest, these seed samples were placed in plastic bags and sent to the Grain Research Laboratory in these sealed plastic bags. Some of these spring canola samples showed very high moisture; it was hypothesized that the samples got moldy during the time it took them to reach our laboratory.

Twelve of the moldiest samples were tested for microbial contaminants (Table 2). No consistent pattern could be established as both mold and bacteria were present. Six of the tested samples were positive for Penicillium, with some Aspergillus. It has been suggested that Aspergillus and Penicillium were storage fungi and did not infest grains in the field (Williams and McDonald, 1983). This seemed to agree with our post-harvest contamination hypothesis - the samples got moldy during the time it took them to reach our laboratory due to storage of high moisture samples in a plastic bag. Seven of these samples also showed the presence of Alternaria. Alternaria is a well-known pathogen for all canola varieties and is widely present in the Canadian prairies (Canola Council of Canada). Five of the twelve samples were greatly contaminated by bacteria so no other pathogens could grow on these samples. It was also noted that one sample was positive for Fusarium; however, it was not a toxigenic species.

Of the 161 spring canola samples, 55 were graded Canola, No.1 Canada (34.2%), 41 were graded Canola, No.2 Canada (25.5%), 33 samples graded Canola, No.3 Canada (20.5%) and 32 samples graded Sample (19.9%), respectively. Samples were downgraded due to the high levels of total damaged seeds associated with sour, musty and rancid odors. The seed color was not natural; an orange tint was observed once the seeds were crushed. It is likely that some producers did not send in samples when they determined that their spring canola seeds were of very low quality. As a result, the true percent of 2017 spring canola graded Canola No. 1, Canada might be lower than what we found in our research project.

To study the effect of the spring harvest on the canola quality, the canola spring quality data have to be compared to quality data of autumn harvested canola samples. Since 2016 harvest was stopped for several weeks due to snow, the 2016 autumn harvested samples were grouped using the combining dates supplied by the producers on the envelopes. We made the assumption that samples harvested in November were harvested after the snow even if this was not clearly indicated on the envelope, and samples identified as snowed-in canola by producers were added to the November samples. The results of the quality analyses (oil, protein, chlorophyll and total glucosinolate contents of the seed and free fatty acid content of the oil) of Canola, No. 1 Canada samples harvested during various times of the 2016 harvest (August to October, November to December, January 2017 and Spring 2017) and individually analyzed by reference methods are presented in Tables 3 to 5. The samples were segregated into 4 harvest times: August to October 2016 (before the snow), November-December 2016 (after the snow), January 2017 (winter 2017) and April to June 2017 (Spring 2017). Statistical analyses showed that there was no difference for oil, protein and chlorophyll contents between the 4 groups of seed samples. A difference was observed for total glucosinolate content with seeds harvested during January 2017 and spring 2017 showing higher average and median results (Table 4) than the seeds harvested in August to October 2016 and November-December 2016. The difference was apparent; however, two µmol of glucosinolates per g of seed are likely not going to affect the quality of the canola meal produced during crushing. The free fatty acid (FFA) content of the oil showed significant difference according to the time of harvest (Table 5). Seeds harvested in winter (January 2017) and spring 2017 had much higher (FFA) than the seeds harvested during autumn (August to October 2016 and November-December 2016).

Tables 6 to 8 present the oil, protein, total glucosinolates and free fatty acid contents for all samples individually analyzed for the 2016 harvest. Oil, protein and total glucosinolate contents (Tables 6 & 7) were not affected by the grade of the canola samples (no statistical difference). Chlorophyll content of the seed and free fatty acid content of the oil were greatly affected by the grade (Pr > F was 0.0028 and < 0.0001, respectively). Chlorophyll content averages increased with the grade for samples harvested in August to October 2016 and November to December 2016, confirming that the main degrading factor was seed immaturity signified by distinctly green seed counts (Table 7). For samples harvested during spring 2017, chlorophyll content averages of the various grade remained constant (Table 7), confirming that the degrading factor was not green seed counts. The 2017 spring canola was mainly downgraded for damage as the seed hulls showed various degrees of discoloration (weathering) and once crushed the canola seed meal showed an orange tint quite different from the usual pale yellow of the seed. All seeds in the lower grade also exhibited an odor suggesting the seeds were getting moldy or rancid. Free fatty acid content averages were higher in the samples harvested in January 2017 and in spring 2017 (Table 8). The seeds were covered in snow, which is a high moisture environment; therefore, it was expected that hydrolytic enzymes would be activated with the triacylglycerides of the oil being degraded to produce free fatty acids. In the field, seeds were in contact with mould and bacteria which could also produce hydrolytic enzymes to degrade the seed triacylglycerides.

The orange tint of the spring harvest canola suggested that the seeds were oxidized; therefore, oxidation products such as hydroperoxides and aldehydes should be in high amounts in these seeds. The next step of the project will be to measure the oil oxidation products to assess the oxidation range of the spring canola seed oils and to compare it to the oils of canola harvested in August to October 2016 and November to December 2016.

Methods

Oil content: a pulse-NMR method (ISO 10565:1992) was used to determined seed oil content. The instrument was calibrated using the oil content reference method (ISO 659).

Protein, total glucosinolate and chlorophyll contents: Protein, total glucosinolates and chlorophyll contents were determined by Near-infrared spectroscopy using a Foss 6500. The instrument was calibrated using the various reference methods.

Fatty acid composition of the oil: A cold extraction method using 20 g of ground seed and twice 30 ml of petroleum ether was used to extract enough oil to determine the fatty acid composition and the free fatty acid content for each sample. Fatty acid composition of the oil was determined according to a modified ISO 12966-2:2017 (fatty acid methyl ester preparation) using sodium methoxide and a modified ISO 12966-1:2014 (GC analysis). The iodine value of the oil was calculated from the fatty acid composition according to AOCS Recommended Practice Cd 1c-85 (1995, 1997).

Free fatty acid content of the oil: The free fatty acid content of the oil was determined using a modified method developed by Ke and Woyewoda (1978). Alkali blue 6B was the color indicator used for the analysis.

Table 2: Summary results of the microbial analyses of 12 spring canola samples – Analyses performed at the Grain Research Laboratory by Dr. Graefenhan.
Canola Sample No. Surface sterilized (Yes/No) Alternaria Aspergillus Clado-sporium Fusarium Helmintho-sporium Mucor Penicillium Bacteria
Sample # 3 Yes (20 seeds)
No (30 seeds)
1

1

3
Sample # 5 Yes (20 seeds)
No (30 seeds)
13
16
2
13

1
1

24
Sample # 8 Yes (20 seeds)
No (30 seeds)
1
2
3
8
24
1
20
Sample # 9 Yes (20 seeds)
No (30 seeds)

30
Sample # 10 Yes (20 seeds)
No (30 seeds)

30
Sample # 17 Yes (20 seeds)
No (30 seeds)
8
5
6
8
1
1

30
Sample # 23 Yes (20 seeds)
No (30 seeds)
11
8

4

1
3
1

29
Sample # 34 Yes (20 seeds)
No (30 seeds)

1
4
30
Sample # 40 Yes (20 seeds)
No (30 seeds)
16
13
1
1

1?
7
30
Sample # 46 Yes (20 seeds)
No (30 seeds)
6
30
Sample # 47 Yes (20 seeds)
No (30 seeds)
20
29
1
30
Sample # 48 Yes (20 seeds)
No (30 seeds)
6
30
Table 3: Summary statistic – Oil and protein contents of canola samples graded Canola No. 1 Canada harvested before snow (August-October 2016), after snow fall (November-December 2016), during winter 2017 (January 2017) and spring 2017 (April-May/June 2017).
Variable Oil content (%, 8.5% moisture) Protein (%, 8.5% moisture)
Harvest time Aug to Oct 2016 Nov to Dec 2016 Jan 2017 Spring 2017 Aug to Oct 2016 Nov to Dec 2016 Jan 2017 Spring 2017
N 91 53 3 52 91 53 3 52
Mean 44.2 44.4 44.6 44.6 20.5 20.9 20.5 20.8
Std Dev 2.9 1.8 0.7 2.2 2.4 1.7 0.6 2.4
Min 38.4 40.9 43.8 38.9 15.2 17.1 20.0 13.3
Max 50.4 48.0 45.1 50.9 26.0 23.9 21.2 25.4
Median 44.1 44.2 44.8 44.2 20.5 21.1 20.2 21.3
One way ANOVA
Pr > F 0.8912 0.7957
Statistically different No No
Table 4: Summary statistic – Chlorophyll and total glucosinolate contents of canola samples graded Canola No. 1 Canada harvested before snow (August-October 2016), after snow fall (November-December 2016), during winter 2017 (January 2017) and spring 2017 (April-May/June 2017).
Variable Chlorophyll content (mg/Kg, as is) Total glucosinolate content (µmol/g, 8.5% moisture)
Harvest time Aug to Oct 2016 Nov to Dec 2016 Jan 2017 Spring 2017 Aug to Oct 2016 Nov to Dec 2016 Jan 2017 Spring 2017
N 91 53 3 52 91 53 3 52
Mean 13 13 10 13 10 10 12 12
Std Dev 7 5 1 5 2 2 2 2
Min 2 4 9 0 5 6 10 7
Max 37 29 11 25 19 13 13 15
Median 11 12 10 14 10 10 12 12
One way ANOVA
Pr > F 0.8218 0.0027
Statistically different No Statistically different
Table 5: Summary statistic – Free fatty acid content of the oil from canola samples harvested before snow (August-October 2016), after snow fall (November-December 2016), during winter 2017 (January 2017) and spring 2017 (April-May/June 2017).
Variable Free fatty acid content of the oil (%, as oleic acid)
Harvest time Aug to Oct 2016 Nov to Dec 2016 Jan 2017 Spring 2017
N 91 53 3 52
Mean 0.17 0.35 0.88 0.43
Std Dev 0.12 0.3 0.59 0.2
Min 0.03 0.07 0.21 0.1
Max 0.77 1.35 1.35 1.07
Median 0.15 0.26 1.06 0.42
Pr > F <0.001
Statistically different Extremely
Table 6: Summary statistic – Oil and protein contents of all individually analyzed canola samples harvested before snow (August-October 2016), after snow fall (November-December 2016), during winter 2017 (January 2017) and spring 2017 (April-May/June 2017).
Harvest time Grade Percent in grade N Oil content (%, 8.5% moisture) Protein content (%, 8.5% moisture)
Mean Min Max Median Mean Min Max Median
Aug - Oct 2016 1 86.7 91 44.2 38.4 50.2 44.2 20.5 15.2 26 20.5
Aug - Oct 2016 2 7.6 8 44.4 41.4 48.6 44.3 20.7 17.6 24 20.5
Aug - Oct 2016 3 1.0 1 42.2 20.6
Aug - Oct 2016 SPLE 4.8 5 41.5 39.4 43.5 41.5 20.6 18.8 22.7 20.7
Aug - Oct 2016 All 100 105 44.2 38.4 50.2 44.1 20.6 15.2 26 20.5
Nov - Dec 2016 1 93.0 53 44.4 40.9 48.0 44.2 20.9 17.1 23.9 21.1
Nov - Dec 2016 2 3.5 2 43.7 43.4 43.9 43.7 20.6 20.3 21 20.7
Nov - Dec 2016 3 1.8 1 44.4 18.3
Nov - Dec 2016 SPLE 1.8 1 44.6 20.2
Nov - Dec 2016 All 100 57 44.4 40.9 48.0 44.2 20.8 17.1 23.9 21
January 2017 1 100 3 44.6 43.8 45.1 44.8 20.5 20 21.2 20.2
January 2017 All 100 3 44.6 43.8 45.1 44.8 20.5 20 21.2 20.2
Spring 2017 1 34.0 55 44.6 39.9 50.9 44.2 20.8 13.3 25.4 21.3
Spring 2017 2 25.3 41 45.1 38.9 48.2 45.6 20.8 17.5 23.8 20.8
Spring 2017 3 20.4 33 45.8 41.5 50.3 45.3 21.6 18.4 25.0 21.8
Spring 2017 SPLE 19.8 32 44.9 39.5 48.2 45.4 22.0 16.3 26.1 21.5
Spring 2017 All 100 161 45.1 38.9 50.9 45.0 21.2 13.3 26.1 21.3
Table 7: Summary statistic – Chlorophyll and total glucosinolate contents of all individually analyzed canola samples harvested before snow (August-October 2016), after snow fall (November-December 2016), during winter 2017 (January 2017) and spring 2017 (April-May/June 2017).
Harvest time Grade Percent in grade N Chlorophyll content (mg/Kg, as is) Total glucosinolate content (µmol/g, 8.5% moisture)
Mean Min Max Median Mean Min Max Median
Aug - Oct 2016 1 86.7 91 13 2 37 11 10 5 19 10
Aug - Oct 2016 2 7.6 8 32 16 54 31 10 8 12 11
Aug - Oct 2016 3 1.0 1 44 13
Aug - Oct 2016 SPLE 4.8 5 18 14 24 17 12 8 15 14
Aug - Oct 2016 All 100 105 15 2 54 12 11 5 19 11
Nov - Dec 2016 1 93.0 53 13 4 29 12 10 6 13 10
Nov - Dec 2016 2 3.5 2 32 23 41 32 12 10 14 12
Nov - Dec 2016 3 1.8 1 45 13
Nov - Dec 2016 SPLE 1.8 1 45 13
Nov - Dec 2016 All 100 57 14 4 45 12 10 6 14 10
January 2017 1 100 3 10 9 11 10 12 10 13 12
January 2017 All 100 3 10 9 11 10 12 10 13 12
Spring 2017 1 34.0 55 13 ND 25 14 12 7 15 12
Spring 2017 2 25.3 41 13 7 25 12 11 6 19 11
Spring 2017 3 20.4 33 14 3 41 12 11 6 25 10
Spring 2017 SPLE 19.8 32 15 ND 58 13 9 4 26 9
Spring 2017 All 100 162 14 ND 58 13 11 4 26 11
ND: below the limit of detection
Table 8: Summary statistic – Free fatty acid contents of the oil from individually analyzed canola samples harvested before snow (August-October 2016), after snow fall (November-December 2016), during winter 2017 (January 2017) and spring 2017 (April-May/June 2017).
Harvest time Grade Percent in grade N Free fatty acid content of the oil (% as oleic acid)
Mean Min Max Median
Aug - Oct 2016 0.17 0.03 0.77 0.15
Aug - Oct 2016 2 7.6 8 0.35 0.08 0.96 0.3
Aug - Oct 2016 SPLE 4.8 5 0.35 0.08 0.96 0.3
Aug - Oct 2016 All 100 105 0.22 0.03 2.8 0.16
Nov - Dec 2016 1 93.0 53 0.35 0.07 1.35 0.26
Nov - Dec 2016 2 3.5 2 0.34 0.13 0.54 0.34
Nov - Dec 2016 3 1.8 1 1.63
Nov - Dec 2016 SPLE 1.8 1 0.67
Nov - Dec 2016 All 100 57 0.38 0.07 1.63 0.27
January 2017 1 100 3 0.88 0.21 1.35 1.06
January 2017 All 100 3 0.88 0.21 1.35 1.06
Spring 2017 1 34.0 55 0.43 0.1 1.07 0.42
Spring 2017 2 25.3 41 0.87 0.34 1.99 0.8
Spring 2017 3 20.4 33 1.34 0.38 3.02 1.07
Spring 2017 SPLE 19.8 32 1.67 0.75 4.77 1.41
Spring 2017 All 100 162 0.94 0.1 4.77 0.80

References

AOCS Official Method Ba 4e-93 (1995, 1997). Protein content by combustion method.

ISO 10519:1997 (E). Rapeseed-Determination of chlorophyll content - Spectrometric method.

Canola Council of Canada: Alternaria black spot (available July 2017).

ISO 9167–3: 2007 (E). Rapeseed - Determination of glucosinolate content—Part 3: Spectrometric method for total glucosinolates by glucose release.

Ke, P.J. and A.D. Woyewoda (1978). A titrimetric method for determination of free fatty acids in tissues and lipids with ternary solvents and m-cresol purple indicator. Analytica Chemica Acta, 99, 387–391.

Williams,R.J. and D.McDonald (1983). Grain molds in the tropics: problems and importance. Annual Review of Phytopathology, 21, 153, 178

Acknowledgments

The Grain Research Laboratory acknowledges the cooperation of the canola producers, grain handling offices, and oilseed crushing plants in western Canada for supplying the canola samples for this project. The assistance of the Industry Services Division of the Canadian Grain Commission in grading all the received samples is also acknowledged. The technical assistance of the Oilseeds staff, Grain Research Laboratory is recognized.

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