An HPLC method to determine o-tyrosine in chicken meat

Abstract

The lack of analytical methods to establish whether or not a food product has been irradiated, and to what dose, if a major obstacle to the wider use of the food irradiation process. o-Tyrosine produced during irradiation of protein-containing foods appears to be a promising marker for this purpose. An HPLC/fluorescence method that allows accurate quantitation of 0.1 ng of o-tyrosine has been developed. The method involves freeze-drying of the sample, acid hydrolysis, solid-phase extraction, fractionation by HPLC, and, in some cases, a second chromatographic separation (HPLC) of the collected fraction. This method was used to determine the radiation dose yield of o-tyrosine in irradiated chicken breast. The results show that there is a linear relationship between the irradiation dose and the yield of o-tyrosine in irradiated chicken meat.

Detection of Irradiation of Meats by HPLC Determination for o-Tyrosine Using Novel LASER Fluorometric Detection with Automatic Pre-column Reaction.

“…Several studies have shown that this procedure is useful for detection of irradiation of foods. 1,2) It was demonstrated that this chemical reaction is affected by temperature, oxygen pressure, and absorbed dose. 3,4) There are conflicting results in regard to the presence of o-tyrosine in non-irradiated intact system; with some researchers detecting it, 5,6) and others not.…”

Detection Methods for Irradiated Foods

“…Offermanns and McDoughall (1991) have used HPLC for the estimation of o‐tyrosine in chicken meat and reported that there was a linear relationship between irradiation dose and yield of o‐tyrosine. But some researchers reported the presence of o‐tyrosine in nonirradiated samples of food in lesser quantities.…”

Identification of irradiated meats by determining o- and m-tyrosine as markers

“…Though these approaches show promise, no extensive testing has been performed. Since o-tyrosine was much easier to separate from p-tyrosine and other complex sample matrices, most methods only proposed the use of o-tyrosine as a potential marker for the detection of radiation processed food (Aflaki et al, 2010; Offermanns & McDougall, 1991;Chuaqui-Offermanns et al, 1993;Hein et al, 2000;Miyahara et al, 2000Miyahara et al, , 2002. In our study, quantitative determination of two tyrosine isomers in irradiated chicken, pork, beef, and hairtail was carried out by LC-FLD and LC-MS/MS in parallel, both using external calibration.…”

“…Since tyrosine positional isomers are formed from the free phenylalanine as well as the phenylalanine bounded in proteins after irradiation, the potential of using one or two specific isomers as markers in irradiated foods for dose estimation has been evaluated by chromatography (Glidewell, Deighton, Goodman, & Hillman, 1993;Stevenson & Stewart, 1995). Based on the fact that there is a linear relationship between irradiation dose and o-tyrosine yield, several methods have been reported for the quantitative determination for irradiated foods (Aflaki, Roozbahani, & Salahinejad, 2010;Chuaqui-Offermanns & McDougall, 1991;Chuaqui-Offermanns, McDougall, & Guerrero, 1993;Miyahara et al, 2000Miyahara et al, , 2002. The majority of these methods only took protein-bound tissue as the source of sample, however, an interesting attempt was proposed by analyzing non-protein-bound o-tyrosine in shrimp.…”