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Detection of Free Radicals in Irradiated Popcorn Using Electron Paramagnetic Resonance

By Jonathan Hamilton and Melvin Figueroa. Detection of Free Radicals in Irradiated Popcorn Using Electron Paramagnetic Resonance. Outline. Review of Jargon Three Sources of Irradiation Cobalt Irradiation Plant History What items are irradiated? Questions that prompted our hypothesis.

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Detection of Free Radicals in Irradiated Popcorn Using Electron Paramagnetic Resonance

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  1. By Jonathan Hamilton and Melvin Figueroa Detection of Free Radicals in Irradiated Popcorn Using Electron Paramagnetic Resonance

  2. 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

  3. 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)?

  4. 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.

  5. Cobalt Irradiation Plant Source: www.foodtechservice.com

  6. 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/foodirradiation.htm

  7. What items are irradiated? Irradiation Medical Supplies Astronaut Food Food Mail

  8. 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?

  9. 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

  10. Electromagnetic Spectrum Source: www.spacetoday.org

  11. Table

  12. 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

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

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

  15. Results Does Electron Paramagnetic Resonance at Low Frequency detect the difference between irradiated and unirradiated samples?

  16. A Closer Look

  17. More information Irradiated Microwaved Popcorn

  18. Conclusions • There is a difference between microwaved and untreated popcorn. Microwaving the popcorn changes the Mn+2 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.

  19. Working in the Lab

  20. Instrumentation

  21. Thank You! Richard Hunter, President/CEO Food Technology Service Center for Integrating Research and Learning Staff Hans Van Tol Saritha Nellutla Gina LaFrazza Naresh Dalal Pat Dixon

  22. Conclusion 

  23. Sources • http://www.cdc.gov/ncidod/dbmd/diseaseinfo/foodirradiation.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

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