The practical application of 3-methylhistidine in determining the lean meat content of food products

Protein-bound 3-methylhistidine, which is present at similar concentrations in various meat species but absent from non-meat proteins, was used to estimate the lean meat content of a range of retailed meat products. The results of the application of this novel method were compared and contrasted with those using standard methods of product analysis. The presence of textured soya protein in products was determined using polyacrylamide gel electrophoresis. Formulae for the calculation of the fat-free lean meat content on the bases of (i) the 3-methylhistidine index for muscle protein and (ii) the connective tissue content, are given. The lean meat contents of products calculated on these bases were found to be of the same order as, but generally lower than, those obtained using standard methods. This was considered to be due to the presence of non-meat proteins, of added connective tissue and/or certain types of offal. These would not be included in the lean meat content, as calculated by the 3-methylhistidine index, but could be legitimately included in the meat content calculated using standard methods according to current practice. A new interpretation of ‘meat’ in terms of 3-methylhistidine content is given.