Distillers Dried Grain and Solubles (DDGS) is a by-product from the ethanol fermentation process that is sold to livestock producers as feed. Contamination of the wheat or corn feedstock by the Fusarium mycotoxin deoxynivalenol (DON) limits the use of DDGS for this purpose.

Ionizing radiation such as that produced by electron accelerators can destroy the Fusarium organism and has the potential to eliminate DON. The objective of this work was to investigate the effect of electron beam (EB) irradiation on DON concentrations in samples taken from various stages in the ethanol process where industrial-scale electron beam treatment can potentially be incorporated.


Procedure and Project Activities:

Five separate samples were collected from a 38.56 tonne lot of Canadian wheat containing 5.1 ppm DON processed at the Husky Energy ethanol plant in Minnedosa, Manitoba. These samples included the wheat used in the fermentation process; the mash or stillage remaining after the ethanol was removed by distillation; distillers solubles (a liquid fraction produced by centrifugation of the stillage); wet distillers grain (the solid collected by centrifugation of the stillage); and DDGS (produced after drying the recombined wet distillers grain and distillers solubles).

Portions of each sample were electron treated at Acsion’s facility in Pinawa to one of five doses in the 2 - 55 kGy range. After irradiation, the samples containing liquid (stillage, wet distillers grain, and distillers solubles) were freeze dried. The 25 electron beam treated samples and the 5 untreated controls were analyzed in duplicate for DON content by gas-chromatography – mass spectrometry at the Canadian Grain Commission’s Grain Research Laboratory.


Results and Discussion:

The DON level in the wheat was 5.1 ppm. Much lower levels of 3-acetyl DON (0.09 ppm) and 15-acetyl DON (0.10 ppm) were also detected in the unprocessed wheat. No other Fusarium trichothecene toxins were detected in the unprocessed wheat or in the processed fractions. DON levels in the untreated samples of stillage, wet distillers grain, distillers solubles and DDGS were 4.3 ppm, 4.0 ppm, 4.9 ppm, and 2.0 ppm respectively. The effects of EB treatment on DON levels in the samples are shown in tables 1-5. This data was not corrected for method recovery in the analyses, which varied from 85% to 106%.


Table 1. Effect of EB Treatment on DON Content of Wet Distillers Grain

Dose (kGy)	Average DON Content (ppm)	Std Dev
0	4	0.14
2.9	4.65	0.07
5.1	4.1	0.57
10.6	3.3	0.42
21.2	3.4	0.00
51.4	2.05	0.35

Table 2. Effect of EB Treatment on DON Content of Distillers Solubles

Dose (kGy)	Average DON Content (ppm)	Std Dev
0	4.9	0.28
2.6	4.6	0.42
5.4	4.3	0.42
10.6	3.75	0.49
21.4	3.05	0.21
55.8	1.15	0.07

Table 3. Effect of EB Treatment on DON Content of Whole Stillage

Dose (kGy)	Average DON Content (ppm)	Std Dev
0	4.3	0.28
2.6	4.6	0.28
5.5	3.9	0.14
10.7	3.6	0.14
22.3	2.6	0.00
51.5	1.05	0.07

Table 4. Effect of EB Treatment on DON Content of Wheat Feedstock

Dose (kGy)	Average DON Content (ppm)	Std Dev
0	5.10	0.14
2.7	4.70	0.14
5.3	4.65	0.07
11.1	4.70	0.00
21.7	4.55	0.07
54.4	4.25	0.07

Table 5. Effect of EB Treatment on DON Content of DDGS

Dose (kGy)	Average DON Content (ppm)	Std Dev
0	2	0.14
2.6	2.1	0.14
5.3	2.1	0.14
10.6	2.05	0.21
21.4	2.2	0.00
51.8	2.1	0.14

DON levels in wet distillers grain, distillers solubles, and whole stillage decreased with increasing EB irradiation dose. At the highest doses used, EB treatment reduced DON concentrations by 48.1% 75.5%, and 74.4% respectively relative to the concentration in the untreated control samples.

EB treatment reduced DON concentrations in the wheat by a maximum of 17.3% at the highest dose used and had no affect on DON concentrations in DDGS. These results are likely due to the lower water content in these samples compared to the production intermediates. In the absence of significant moisture, the interaction of radiation with the material would be through a direct effect, while in an aqueous environment, radiation will convert water into highly reactive free radicals which will attack and breakdown organic molecules such as DON.

The DON level in DDGS was approximately 59% lower than the concentration in the wheat. This is typical for the process used at the Minnedosa plant and is assumed to be due to the high temperatures used for flash drying of the product at the front of the drying process. The combination of EB treatment with drying could reduce the final DON levels in DDGS by 90% or more, indicating that EB treatment may be a method for reducing DON levels in DDGS on an industrial level.


Conclusions:

Electron beam treatment of DDGS production intermediates can reduce DON levels up to 75%. Coupled with the loss incurred in the drying step to produce DDGS, the total drop in DON content could exceed 90%. These results indicate that EB treatment may provide a method for reducing DON levels in DDGS on an industrial scale.


Acknowledgements:

Acsion gratefully acknowledges the financial assistance provided by the Governments of Manitoba and Canada through the Canada-Manitoba Agri-Food Research and Development Initiative (ARDI), without which this project would not have been possible.

Acsion thanks Husky Energy for supplying the samples and the Canadian Grain Commission for analyzing the samples for DON content.


Applicant:
Terry Stepanik Acsion Industries Pinawa, Manitoba R0E 1L0 Canada


Researchers:
T. M. Stepanik and D. Kost, Acsion Industries Inc.; and T. Nowicki and D. Gaba, Canadian Grain Commission
Manitoba Agriculture, Food and Rural Initiatives