This presentation on reducing aflatoxin contamination in shelled corn was given at the 2nd All Africa Post-Harvest Congress & Exhibition in Addis Ababa. The focus of the presentation was on coming to an understanding about the performance of using high voltage cold plasma to potentially reduce aflatoxin. The research was able to conclude that this high voltage system is effective in degrading aflatoxins in shelled corn. The lead researchers from Iowa State University, who prepared the presentation, are making it available via the Consortium for Innovation in Post-Harvest Loss and Food Waste Reduction SlideShare account. Iowa State University is a member of the Consortium.

1. Reducing Aflatoxin Contamination in Shelled
Corn Using High Voltage Atmospheric Cold
Plasma (HVACP) Technology
Kizito Nishimwe1, Hu Shi1, Kevin Keener1, Dirk Maier2
1Department of Food Science and Human Nutrition
2Department of Agricultural and Biosystems Engineering
THE 2ND ALL AFRICA POSTHARVEST CONGRESS & EXHIBITION
Addis Ababa, Ethiopia
September 17 -20, 2019

2. High Voltage Atmospheric Cold Plasma
(HVACP)
• HVACP is an emerging technology with low
operating cost using only atmospheric air and
electricity.
• HVACP ionizes air using high voltage electricity
(up to 100 kV) and generates variety of reactive
gas species via dielectric barrier discharge
(DBD) between electrodes.
• HVACP generates a plasma composed of
photons, ions, free electrons, and atoms in their
fundamental or excited state with a net neutral
charge.
Plasma Generation

3. What is Plasma?
Lightning
Fluorescent Neon Tube
https://stock.adobe.com/images/plasma-fluorescent-neon-sign-on-brickwall-front-view/170578698
Plasma called the 4th state of the matter
https://www.balticnet-plasmatec.org/plasma-technology/
Energy
Energy
Energy
Solid
Liquid
Gas
Plasma

4. Shi et al., 2017 (a)
HVACP – Experimental set-up
• Ozone (O3)
• Atomic oxygen (O)
• Superoxide (O2•−)
• Peroxide (O2
−2 or H2O2)
• Hydroxyl radicals (OH•)
• NxOy (N2O5, NO2, NO3,…
Reactive Gas Species

5. Electrodes
Dielectric barriersSealed box

6. HVACP System Design
Gap:4.44cm
Electrodes
Sealed bag containing sample
Sealed bag containing sample

7. What are Aflatoxins?
• Toxic metabolites produced by a
variety of molds (A. flavus, A.
parasiticus)
• Among the most carcinogenic
substances known:
• IARC classification: Group 1
• "Carcinogenic to humans" There
is enough evidence to conclude that
it can cause cancer in humans
IARC: International Agency for Research on Cancer
https://agra.org/ghana-intensifies-bid-for-eradication-of-aflatoxin-related-losses-
from-agricultural-value-chains/

8. https://agrilinks.org/aflatoxins

9. https://paepard.blogspot.com/2018/04/increasing-awareness-of-and-concerted.html
Sources of Aflatoxin Exposure

10. Experimental Design
Factors Factor levels
Gas type Air (21% O2, 78% N2, 1% others)
MA65 (65% O2, 5% N2, 30% CO2)
Relative Humidity (RH) 5, 40, 80%
Treatment time 1, 2, 5, 10, 20, 30min
 Replicate: 3 times
Samples are prepared by applying 50 µg/ml AFB1 solution in
chloroform into 25g corn sample
After HVACP treatment, samples are stored in sealed bags at
room temperature for 24 h

11. Aflatoxin degradation by HVACP
0
50
100
150
200
250
300
350
400
450
500
0 5 10 15 20 25 30
Aflatoxinlevel(ppb)
Cold plasma treatment time (mins)
Air RH 5% Air RH 40% Air RH 80%
MA RH 5% MA RH 40% MA RH 80%

12. HVACP Capacity to Reduce Aflatoxin Contamination
• Ozone (O3)
• Atomic oxygen (O)
• Superoxide (O2•−)
• Peroxide (O2
−2 or H2O2)
• Hydroxyl radicals (OH•)
• NxOy (N2O5, NO2, NO3,…
Aflatoxin B1Reactive Gas Species
Degradation of
Aflatoxin B1

13. Conclusions
• RH 40 and 80% are more effective in degrading aflatoxin than
RH 5%
• Gas MA65 is more effective in degradation of aflatoxin than
ambient air
• Degradation of aflatoxins by cold plasma follows exponential
decay over time  73 – 92% reduction (storage, stirring)
• HVACP is an effective mitigation technology to degrade
aflatoxins in shelled corn

14. Thank You For Your
Attention
E.Mail: nishimwe@iastate.edu
Questions?