Haem pigment

Hornsey, H. C. (1956). The colour of cooked cured pork. 1. Estimation of the nitric oxide-haem pigments. J. Sci. FoodAgric. 7, 534-540. 

Walters, C. L., Casselden, R. J., and Taylor, A. M. (1967). Nitrite metabolism by skeletal muscle mitochondria in relation to haem pigments. Biochim. Biophys. Acta 143, 310-318. 

Krzywicki, K. 1982. The determination of haem pigments in meat. Meat Sci. 7 29-36. 

Warriss, P.D. 1979. The extraction of haem pigments from fresh meat. J. Food Technol. 14 75-80. 

Figure 48 Relative concentrations of total haem pigments in the dark muscle of cod during a 12-month period. The ordinate is the mean optical density at 512 nm of a 4-cm light path.

P2. Perryman, P. W., Richards, D. H., and Holbrook, B., Simultaneous microdetermination of serum bilirubin and serum haem-pigments. Biochem. J. 66, 61P (1957)... 

Fig. 10.49. Schematic diagram of the haem cycle, in which the haem pigment is produced from ALA (<5-amino levuHnic acid). The photodynamic action of protoporphyrin IX leading to tissue necrosis is also indicated [10.182]...

Of the substances that are present in foods, the most important photosensitisers are chlorophylls, phaeophytins, haem pigments and riboflavin. In vegetable oils, chlorophylls (and their degradation... 

The resulting alkoxyl and peroxyl radicals increase the autoxidation reaction rates of initiation and propagation phases, since the rate of cleavage of hydroperoxides by metal ions is much faster than the formation of radicals ab inicio. Metal ions and non-ionised salts may react in this way (Figure 3.65). Of the metals bound in complexes, some are effective, but some are ineffective. Metals may also become less effective in the presence of fats if micelles are formed. The catalyst for the oxidation of Kpids may be bound iron complexes. Iron bound in haem pigments has the same catalytic activity as the ions Fe + a Fe +, in aqueous solutions it is even more active, as it catalyses the cleavage of hydroperoxides as follows ... 

The third mechanism of catalysis of hpid autoxidation by haem pigments is a photosensitised reaction and oxidation of lipids by either singlet oxygen or free radicals. The fourth mechanism assumes hydroxyl radical attack, in which haem iron is released in an ionic form, which then catalyses the oxidation of lipids in the same way as non-haem iron. 

The loss of vitamin C may also occur during reactions of ascorbic acid with some of the reactive food components. In particular, reactions of ascorbic acid with quinones generated by enzymatic browning reactions, reactions with nitrites and haem pigments in meat and meat products are technologically significant. 

These pigments contribute to the colour of muscle tissue only very sKghtly. Haem pigments can similarly be found in the plant kingdom in the form of cytochromes and some oxidoreductases, such as catalase and peroxidase (see Section 6.2.2.7). 

Several other haem pigments also occur in muscle tissue (such as cytochromes that carry out electron transport) containing iron in a similar porphyrin-protein complex to that in myoglobin. 

Table 9.2 Haem pigments contents In beef and pork.

Table 9.4 Haem pigments contents in various animals.

Meat Haem pigments (mg/kg) Meat Haem pigments (mg/kg)... 

Table 9.5 Haem pigments contents in dark and iight fish muscies. ...

From the nutritional point of view, haem pigments are of considerable importance in the supply of iron to the human organism. The so-caUed haem iron, which includes iron bound in myoglobin and haemoglobin and iron bound in muscle respiratory enzymes, is absorbed in the body at a level of 10-30%, whQe non-haem iron from only 1-5%. 

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