Abstract
During y-irradiation (5 kGy) of aqueous tryptophan (Trp) solutions small amounts of 5-, 6-, and 7-hydroxytryptophan (OH-Trp) (0.04-0.08 Mol-%) are formed. Protein rich food like shrimps contain reasonable amounts of non-protein bound Trp (100 mg/kg). In order to detect the treatment of shrimps with y-irradiation a method for the determination of OH-Trp in y-irradiated shrimps was developed. After homogenization, squeezing of shrimp samples and protein precipitation, a two-step-SPE-clean up was performed using a C18-cartridge and a propylsulfonic acid cation-exchange SPE followed by HPLC analysis with electrochemical detection (750 mV). Results showed that 5-OH-Trp contents in shrimp samples increased with applied doses up to 3 kGy and then decreased with higher doses. Other OH-Tip isomers were not detectable in the irradiated shrimps. Similarly no formation of 4-, 6-, and 7-OH-Tip was detected in model solutions containing the same amino acid composition as in shrimps. This indicates a suppression of the reaction of OH-radicals with Trp by the 300 fold molar excess of other amino acids acting as well as radical scavengers. Therefore, non-physiological OH-Tip isomers formed from free Tip are not suitable as markers for the detection of y-irradiated protein-rich foodstuff.
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Kleeberg, K.K., Müller, A., Simat, T.J., Steinhart, H. (2003). Suitability of Tryptophan Radiation Products as Markers for the Detection of γ-Irradiated Protein Rich Food. In: Allegri, G., Costa, C.V.L., Ragazzi, E., Steinhart, H., Varesio, L. (eds) Developments in Tryptophan and Serotonin Metabolism. Advances in Experimental Medicine and Biology, vol 527. Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-0135-0_80
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DOI: https://doi.org/10.1007/978-1-4615-0135-0_80
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