The influence of fibre-type composition and associated biochemical characteristics on the acid buffering capacities of several beef muscles.

Several beef forequarter muscles were investigated for fibre-type composition, total pigments, total nitrogen, non-protein nitrogen, anserine, carnosine and inorganic phosphorus contents, ultimate pH (pH(u)) and acid buffering capacities. In general, the predominantly 'red' fibre-type muscles had significantly higher (P<0·05) pH(u) values and total pigment concentrations than the predominantly 'white' fibre-type muscles which had significantly higher (P< 0·05) total nitrogen, non-protein nitrogen and carnosine contents and also significantly higher (P< 0·05) acid buffering capacities. The relationships between the various biochemical parameters of all the muscles studied and their acid buffering capacities were investigated by correlation matrix. The higher buffering capacities of the 'white' fibre-type muscles over the pH range pH(u) to pH 5·0 were attributed to their higher contents of carnosine and inorganic phosphorus. However, over the pH ranges pH(u) to pH 4·5 down to pH(u) to pH 3·0, the higher buffering capacities of the 'white' fibre-type muscles were attributed primarily to their higher lactic acid concentrations, as indicated by their low pH(u) values, and also to their higher non-protein nitrogen contents.