A method for extracting carboxy-myoglobin from beef

The present study was conducted to devise a method for the effective extraction of carboxy-myoglobin (COMb) from beef without carbon monoxide dissociation. The ratio of COMb to myoglobin was computed at absorptions of wavelengths 541 and 551 nm, which characterize COMb and the isosbestic point between COMb and deoxy-myoglobin, respectively. The COMb extraction rate was found to vary with temperature, pH and oxygen conditions. The decrease observed in this rate was inversely proportional to the rise in extraction temperature. The COMb extraction rate was also affected by pH, and the stability of COMb in the extract solution was the highest at pH 8.0-9.0. Moreover, the presence of oxygen was found to disturb COMb extraction. According to these results, nearly all COMb could be extracted from carbon-monoxide-treated beef under stirring conditions in pH 8.5 deoxidized buffer, at 1°C, and under N₂ flow with the improved extraction method in this study (98.1 ± 2.7%). The decrement of COMb in the extract was accelerated by light, and the COMb was stable for 20 min in the dark, at 1°C. The extraction conditions for COMb described above should allow the accurate evaluation of COMb in meat tissue.