ELUCIDATION OF THE CHEMICAL-STRUCTURE OF PREFORMED COOKED CURED-MEAT PIGMENT BY ELECTRON-PARAMAGNETIC-RESONANCE SPECTROSCOPY

The preparation of cooked cured-meat pigment (CCMP) has previously bee n reported from our laboratories, but the exact chemical nature of thi s pigment has remained elusive. Electron paramagnetic resonance (EPR) spectroscopy was employed to help provide the answers sought. EPR spec tra of CCMP in an acetone glass revealed that the molecule is paramagn etic and exists as a pentacoordinate mononitrosylheme complex. A well- resolved triplet in the gs region of the spectrum was due to hyperfine splitting of the N-14 nuclei of NO with an unpaired electron. In a py ridine glass, EPR spectra suggest that there was participation of a py ridine molecule with the nitrosylheme complex. Such spectra are typica l of a hexacoordinate species and are similar to those of NO complexes of Fe(II) myoglobin and hemoglobin. Additionally, a loss in resolutio n of the hyperfine structure in the g(3) region was apparent. EPR spec tra of cooked nitrite-cured and CCMP-treated meat, in situ, were simil ar and were identical to that of the preformed CCMP in acetone. Thus, the pigment formed in thermally processed nitrite-cured meat is identi cal to that of CCMP prepared outside the meat matrix and then applied to meat as part of a nitrite-free multicomponent curing system.