Assessment of the previous heat treatment given to meat products in the temperature range 40°–90°C. Part 1: Soluble nitrogen analysis

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Abstract
The aim of this work was to identify a technique which would yield information retrospectively about the heat treatment applied to a meat product in the temperature range 40–90°C. Saline extracts of beef samples (M. longissimus dorsi and M. semi‐membranosus) of known heat treatment, were analysed for soluble nitrogen by Kjeldahl analysis. The amount of residual soluble nitrogen in an extract was found to decrease as the cooking temperature increased, with the major reduction occurring between 40 and 70°C. A good correlation between nitrogen values was obtained for aliquots removed from a continuously heated raw meat extract, 5 mm slices and the centre sections of 60 mm cubes. It was also possible to detect differences in the extent of heating achieved at points between the surface and the centre of the solid piece of meat. These results indicate that it may be possible to estimate in retrospect the approximate maximum temperature reached in an unknown cooked meat sample by reference to a standard curve of soluble nitrogen versus known heat treatment.