Formation of oxo- and hydroxyfatty acids in irradiated chickens

Finely ground chicken skin and subcutaneous fat exposed to gamma radiation from (137)Cs at 0-2°C for up to 10 kGy generated oxofatty acids (OFA) and hydroxyfatty acids (HFA) in the glycerides. Both classes were determined as colored derivatives; OFA as 2,4-dinitrophenylhydrazones, and HFA as esters of pyruvic acid 2,6-dinitrophenylhydrazone. The concentration of OFA increased with increasing irradiation dose but not always linearly. Variations in the concentration of both classes were noted and some chicken lipids failed to form both classes. In the samples where OFA were generated in significant quantities, the absorption maximum of the derivatives shifted toward a higher wavelength with increasing dose due ostensibly to the formation of double bond(s) in conjugation with the oxo group. This shift in absorption maximum was initially considered to be a means for detecting irradiation as well as indicating the dose received with fair accuracy. However, in several instances irradiation of a chicken sample did not result in the formation of significant increases in OFA and therefore this method cannot be used as a definitive test.