Abstract
By electron spin resonance (ESR) spectroscopy, we revealed free radicals in wheat flour before and after γ-ray inrradiation and their thermal behavior during heat treatment. The ESR spectrum of wheat flour before irradiation consists of a sextet centered atg=2.0 and a singlet signal at the sameg-value position. The first one is attributable to a signal with hyperfine (hf) interactions of Mn2+ ion (hf constant, 7.4 mT). The second signal originates from the carbon-centered radical. Upon γ-ray irradiation, however, a new signal with two triplet lines at the low- and high-field ends was detected on the Mn2+ sextet lines. We analyzed the triplet ESR lines as due to powder spectra (rhombicg-tensor symmetry) with nitrogen (14N) hf interactions. This indicates that a new organic radical was induced in the conjugated protein portion of wheat flour by γ-ray irradiation. The intensity of the organic free radical atg=2.0 detected in irradiated wheat flour increased monotonically under thermal treatment. The analysis of the time-dependent evolution process on the basis of the theory of transient phenomena as well as the nonlinear least-squares numerical method provided a unique time constant for the radical evolution in wheat flour during thermal treatment.
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References
Delincée H.: Radiat. Phys. Chem.63, 455–458 (2002)
Dickson J.S. in: Food Irradiation: Principles and Applications (Molins R.A., ed.), pp. 23–36. New York: Wiley 2001.
Dodd N.J.F., Lea J.S., Swallow A.J.: Nature334, 387 (1988)
WHO: Report of a Joint FAO/IAEA/WHO Study Group. WHO Technical Report Series 890. Geneva: World Health Organization (1999)
EN1786: Food Stuffs — Detection of Irradiated Food Containing Bone — Method by ESR Spectroscopy. Brussels, Belgium: European Committee for Standardization 1966.
EN1787: Food Stuffs — Detection of Irradiated Food Containing Cellulose — Method by ESR Spectroscopy. Brussels, Belgium: European Committee for Standardization 1966.
EN1787: Food Stuffs — Detection of Irradiated Food Containing Cellulose by ESR Spectroscopy. Brussels, Belgium: European Committee for Standardization 2000.
Farkas J.: Radiat. Phys. Chem.25, 271–280 (1985)
Edward S., Josephson E.S.: Radiat. Phys. Chem.18, 223–239 (1981)
Löfroth D., Ehrenberg A., Ehrenberg L.: Radiat. Bot.4, 55–467 (1964)
Murrieta H.S., Muñoz E.P., Adam E., Burillo G., Vazquez M., Cabrera E.B.: Appl. Radiat. Isot.47, 1657–1661 (1996)
Stewart E.M. in: Food Irradiation: Principles and Applications (Molins R.A., ed.), pp. 347–386. New York: Wiley 2001.
Szöcs F.: J. Food Sci.67, 2079–2082 (2002)
Ehrenberg A., Ehrenberg L., Löfroth G.: Abh. Dtsch. Akad. der Wiss. Berlin KI. Med.1, 229–231 (1962)
Ukai M., Shimoyama Y.: Radioisotopes51, 501–504 (2002)
Ukai M., Shimoyama Y.: Appl. Magn. Reson.24, 1–11 (2003)
Ukai M., Shimoyama Y.: Appl. Magn. Reson.25, 95–103 (2003)
Ukai M., Shimoyama Y.: J. Food Sci.68, 2225–2229 (2003)
McElroy J., Feher G., Mauzerall D.: Biochim. Biophys. Acta172, 180–183 (1969)
Brudig G.W., Crabtree R.H.: Proc. Natl. Acad. Sci. USA83, 4586–4588 (1986)
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Ukai, M., Shimoyama, Y. Free radicals in irradiated wheat flour detected by electron spin resonance. Appl. Magn. Reson. 29, 315–324 (2005). https://doi.org/10.1007/BF03167019
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DOI: https://doi.org/10.1007/BF03167019