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Diminution Effect on Mycotoxin Content by Different Processing Methods in Barley and Wheat Infected with Fusarium graminearum Oh-Kyung Kwon*, Su-Myeong Hong1, Dal-soon Choi1, Jeom-Sig Lee, You-Chun Song, Un-Goo Ha and S.J. Yang Abstract
The objective of this study is to analyze mycotoxins contents in cereals infected with Fusarium graminearum and consider the reduction of mycotoxin contents by different processing methods in cereals. The result of quantitative analysis showed major contaminants were Deoxynivalenol(DON), Nivalenol(NIV), and Zearalenone(ZEA) and the level of NIV concentration was high in comparison with that of the other mycotoxins. The mycotoxin contents in hulled barley were more than those in naked barley. Total concentration range of mycotoxins detected in marketing barley was 0.284~0.593 ppm and this level was below US/EPA guidelines. Effect of different processing methods on the reduction in mycotoxin contents in barleys indicated water-washed treatment, barley tea process, and alcohol fermentation reduced concentration by 67%, 72.5% and 100%, respectively. The ferment waste produced from alcohol fermentation indicated a low concentration of mycotoxins because of fermentation activity and a decomposition ratio of major mycotoxins in waste showed the order of DON>NIV>ZEA. The residue levels of mycotoxins in boiled barley after washing treatment were unwashed barley 0.347ppm, 1’st washing 0.152ppm, 2’nd washing 0.066ppm, and boiled barley 0.060ppm. In case of wheat, changes of mycotoxin content showed the reducing effect of tempering( 0% water) was the greatest of the three processing methods tested. Media summary
The analysis of mycotoxins contents by different processing method in cereals infected with Fusarium graminearum will show the diminution effect and provide the safety evaluation.
Key Words
Fusarium mycotoxins, Quantitative analysis, Cereals, Diminution effect, Different processing method
Introduction
Mycotoxins deoxynivalenol, nivalenol, and zearalenone are groups of secondary metabolites produced by Fusarium species which induce mycotoxicosis of humans and animals (Desjardins et al 1989; Ichinoe et al 1983; Kim et al 1993). Since the mycotoxins are accumulated in cereals infected with Fusarium graminearum, they have high possibility to affect the crop quality and human safety (Jelinek et al 1989; Luo 1988). The objective of this study is to compare the concentration levels of major mycotoxins and evaluate the reducing effect on mycotoxin contents in cereals of different processing methods. We also considered the relation of mycotoxin content and milled grade of grain.
Methods
Sampling and pretreatment
A comparative study on the concentration levels of mycotoxins was done with 100 barley, 10 wheat samples collected from 4 provinces in Korea.The ground samples were shaken for 1hr with CH3CN/H2O and the filtrates were partitioned with organic solvents after filtering. The evaporated EtOAc layer, which was solved with MeOH was applied to florisil column chromatograph for purification.
Instrument condition for analysis of Fusarium mycotoxins
Detection of DON and NIV was carried out by HRGC/MS method after derivatization with TMS. Concentrations of DON and NIV were determined by HRGC with a DB-5 column (J&W Scientific, US), connected to a HRMS (TSQ7000, Finnigan MAT, US) operation on a resolution of 10,000 using a positive electron ionization source and operating in the selected ion monitoring(SIM) mode. The ionization energy was 70eV and the temperature of ion source and injector was 185 and 280℃.In case of ZEA analysis, the concentration was determined by HPLC(1046A, Hewlett Packard, US) with a RP18 column of 5㎛, 4.6mm(ID) x 150mm(L). The condition of fluorescence detector indicated the wave length of excitation and emission was 236 and 418㎚ respectively. Mobile phase was CH3CN/H20(50/50,v/v) and flow rate was 0.8㎖/min.
Results
Table 1. Changes of mycotoxin contents in hulled barley by different milling rates
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Disease
severity (%)
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Milling
rate (%)
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Mycotoxin content (ppm)
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Total
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DON
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NIV
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ZEA
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Normal
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100
59
50
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0.324
ND
ND
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0.041
ND
ND
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0.293
ND
ND
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ND
ND
ND
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10
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100
59
50
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2.581
0.628
0.178
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0.187
0.030
ND
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2.347
0.586
0.165
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0.047
0.012
0.013
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30
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100
67
59
50
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8.600
1.039
0.923
0.563
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0.452
0.036
0.022
ND
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8.125
0.992
0.890
0.563
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0.023
0.011
0.011
ND
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50
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100
59
50
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16.320
3.372
2.548
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0.897
0.099
0.083
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15.333
3.259
2.435
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0.090
0.014
0.030
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Table 2. Changes of mycotoxin contents in naked barley by different milling rate
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Disease
Severity (%)
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Milling
rate (%)
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Mycotoxin content (ppm)
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Total
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DON
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NIV
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ZEA
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Normal
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100
68
60
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0.286
ND
ND
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0.060
ND
ND
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0.226
ND
ND
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ND
ND
ND
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10
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100
68
60
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2.025
0.428
ND
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0.094
ND
ND
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1.931
0.428
ND
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ND
ND
ND
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30
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100
75
68
60
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2.331
0.763
0.406
0.327
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0.125
0.031
ND
ND
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2.193
0.732
0.406
0.327
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0.013
ND
ND
ND
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50
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100
68
60
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4.932
0.690
0.281
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0.188
0.026
ND
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4.723
0.664
0.281
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0.021
ND
ND
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Table 3. Effect of water-washed treatment on the dimuition of mycotoxin contents in hulled barley
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Grade
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NIV (ppm)
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Total (ppm)
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Barley
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Water-washed
barley (%)
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Barley
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Water-Washed
barley (%)
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First
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0.547
1.130
0.276
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0.105(19)
0.431(38)
0.084(30)
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0.583
1.163
0.288
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0.105(18)
0.446(38)
0.084(29)
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Second
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0.521
0.321
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0.208(40)
0.089(28)
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0.569
0.321
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0.239(42)
0.089(28)
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Offgrade
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0.865
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0.282(33)
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0.961
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0.294(32)
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Average
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0.610
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0.200(33)
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0.640
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0.210(33)
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Range
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0.276~1.130
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0.084~0.431
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0.288~1.163
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0.084~0.446
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Fig. 1. Mycotoxin residues in boiled barley after water washing treatment
Table 4. Changes of mycotoxin contents in wheat by different processing method
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Processing method
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Part
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Mycotoxin content(ppm)
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Total
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DON
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NIV
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ZEA
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Raw-material
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Wheat
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0.751
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0.181
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0.570
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ND
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Tempering
(water 14%)
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Flour
Inner Bran
Outer Bran
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0.202
0.505
0.509
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0.064
0.129
0.130
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0.138
0.376
0.379
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ND
ND
ND
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Tempering
(water 0%)
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Flour
Inner Bran
Outer Bran
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0.117
0.464
0.557
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0.033
0.110
0.169
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0.084
0.354
0.388
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ND
ND
ND
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Korea type
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Flour
Bran
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0.185
0.477
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0.041
0.116
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0.144
0.361
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ND
ND
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Conclusion
1. The tendency of mycotoxin content in cereals
- The kind of mycotoxin : NIV>DON> ZEA
- Barley variety : hulled Barley > naked barley
- Different polishing rate of diseased barley (50%)
- hulled barley (50% polishing) : 16.320→2.548ppm
- naked barley (60% polishing) : 4.932 → 0.281ppm
- wheat part : Outer bran > Inner bran > Flour
- Processing method of wheat flour : Tempering > Korean wheat > Free water
2. Effect of different processing method on the diminution of mycotoxin contents in cereals
- Mycotoxin residues in boiled barley after water washing:
0.347→0.066→0.060ppm
- Water-washed treatment of barley : 0.640 → 0.210ppm
- Alcohol fermentation of barley : 16.32ppm → ND
References
Desjardins AE, Spencer GF, Plattner RD and Beremand MN (1989). Furanocoumarin phytoalexins, trichothecene toxins and infection of Pastinacasativa by Fusarium sporotrichioides. Phytopathology 79, 170-175
Ichinoe M, Kurata H, Sugiura Y and Ueno Y (1983). Chemotaxonomy of Gibberella zeae with special reference to production of trichothecenes and zearalenone. Appl. Environ. Microbiol. 46, 1364-1369
Jelinek CF, Pohland AE and Wood GE (1989) Worldwide occurrence of mycotoxins in foods and feeds-an update. J. Assoc. Off. Anal. Chem. 72, 223-230
Kim JG, Kang HJ, Lee DH, Lee YW and Yoshizawa T (1993). Natural occurrence of Fusarium mycotoxins (trichothecenes and zearalenone) in barley and corn in Korea. Appl. Environ. Microbiol. 59, 3798-3802
Luo XY (1988). Fusarium toxins contamination of cereals in China. Pro. Jpn. Assoc. Mycotoxicol., Suppl. 97-98 
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