Detection of Free Radicals in Irradiated Popcorn Using Electron Paramagnetic Resonance

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Detection of Free Radicals in Irradiated Popcorn
Using Electron Paramagnetic Resonance

• By Jonathan Hamilton and Melvin Figueroa

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Outline

• Review of Jargon
• Three Sources of Irradiation
• Cobalt Irradiation Plant
• History
• What items are irradiated?
• Questions that prompted our hypothesis.
• Experimental design
• A closer look at our samples.
• Results and Conclusions
• Acknowledgements

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Review Jargon

• What is the purpose of Food Irradiation?
• Does irradiation make food radioactive?
• Why is food irradiation sometimes called cold
  pasteurization?
• What is a kilogray? (kGy)
• What is a Tesla?
• What are free radicals?
• What is Electron Paramagnetic Resonance (EPR)?

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Three different sources of irradiation.
Gamma Rays
Electron Rays
X-Rays
Uses Cobalt 60 and Cesium 137. These Unstable
isotopes radiate high energy photons called
gamma rays.
A stream of high energy electrons that are
propelled out of an electron gun.
A powerful x-ray machine is used. A beam of
electrons is directed at a thin plate of gold
producing a stream of x-rays.
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Cobalt Irradiation Plant
Source www.foodtechservice.com
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History
How long do irradiated strawberries last? Can it
be used on all food? What is 4.5 kGy equivalent
to?

• www.cdc.gov/ncidod/dbmd/diseaseinfo/foodirradiatio
  n.htm

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What items are irradiated?
Irradiation
Medical Supplies
Astronaut Food
Food
Mail
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Questions that prompted our experiment

• Is there any difference between conventionally
  popped popcorn and microwave popped popcorn?
• How does irradiation affect popcorn?
• Does Electron Paramagnetic Resonance at Low
  Frequency detect the difference between
  irradiated and unirradiated samples?
• Is there a way to detect whether or not food in
  the grocery store has been irradiated?
• How does microwaving popcorn affect it?

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Experimental Design

• Purpose To detect radical formation in popcorn.
• Purpose Does Electron Paramagnetic Resonance at
  Low Frequency detect the difference between
  irradiated and unirradiated samples?
• Purpose To determine the effect of various
  treatments on popcorn
• Irradiation with Cobalt 60
• Microwaves at 2.45 kHz
• Thermal Convection

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Electromagnetic Spectrum
Source www.spacetoday.org
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Table
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Procedures

• Samples consisted of irradiated, unirradiated,
  ground kernels, popped corn
• We used the X-Band Electron Paramagnetic
  Resonance Magnet
• We put the sample in a fused silica quartz sample
  tube
• The resonance signals were recorded by the
  spectrometer

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A Closer Look At Our Popcorn
Why do free radicals last longer in unpopped
kernels than in popped popcorn?
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Results

• Is there any difference between conventionally
  popped popcorn and microwave popped popcorn?

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Results
Does Electron Paramagnetic Resonance at Low
Frequency detect the difference between
irradiated and unirradiated samples?
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A Closer Look
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More information
Irradiated Microwaved Popcorn
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Conclusions

• There is a difference between microwaved and
  untreated popcorn. Microwaving the popcorn
  changes the Mn2 signal and increases the free
  radical signal.
• Irradiation at low doses has minimal effect on
  the radical signal. At higher doses the EPR shows
  that the radical increases and new radicals are
  formed.
• EPR does detect the differences between
  irradiated and unirradiated samples. The higher
  the doses the higher the radical signal.

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Working in the Lab
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Instrumentation
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Thank You!
Richard Hunter, President/CEO Food Technology
Service
Center for Integrating Research and Learning Staff
Hans Van Tol
Saritha Nellutla
Naresh Dalal
Gina LaFrazza
Pat Dixon
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Conclusion ?
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Sources

• http//www.cdc.gov/ncidod/dbmd/diseaseinfo/foodirr
  adiation.htm
• Delincee, H. Soika, C. Radiation and Physics
  Chemistry 63 (2002) 437-441 Improvement of the
  ESR detection of irradiated food containing
  cellulose employing a simple extraction method
• Korkmaz, M. Polat, M. International Journal of
  Food Science Technology Volume 39 Issue 9 Page
  975 November 2004 An electron spin resonance
  study of radicals induced by radiation in oat
• www.mariner.connectfree.co.uk/html/emr.htm