On the nature and reactivity of the haematin complexes present in intermediate moisture beef

Summary The colour of intermediate moisture (i.m.) beef prepared by cook‐soak equilibration in glycerol was studied. The freshly processed cook‐soak‐equilibrated beef samples were spectrally similar to ordinary cooked beef. With storage at 38°C and 28°C the spectra changed from that typical of cooked meat haemoprotein to one more typical of free haematin. This reaction produced a subjectively detectable change (lightening) in meat colour. The rate of change varied with water activity. However, the amount of haematin that could be extracted by 40% pyridine decreased during storage suggesting that if freed the haematin is either involved in further complexing reactions or broken down to pyrrole fragments and non‐haematin iron. The nature and nutritional availability of the iron in the i.m. beef may depend on these reactions.