Predicting the heating times of beef joints

Abstract Heat transfer coefficients at the surface of a cylinder (80 mm diameter × 160 mm long) were measured with air moving over the cylinder at velocities ranging from 0·15 to 0·6 m/s and temperatures from 65·5 to 175°C. Temperatures within a cylinder of PTFE of the same size and heated for up to 5 h under the same air conditions were measured and compared with predictions obtained using a mathematical model incorporating the measured transfer coefficients. Temperatures measured after heating for 60, 120 and 300 min showed that the maximum variation between measured and predicted lowest internal temperature was 10°C with an average absolute deviation of 2·6°C. Identical tests were carried out using cylinders of beef muscle which showed a maximum difference of 36°C and average absolute deviation of 14°C between measured and predicted lowest internal temperature after 60, 120 and 300 min. Tests also showed large differences, up to 62%, between measured and predicted heating times to a lowest internal temperature of 74°C. These differences were attributed to the model's neglect of evaporation, drip and dimensional changes in the meat during heating. Models for predicting these effects are suggested. After heating the meat to a minimum internal temperature of 74°C, minimum weight loss was achieved by using the highest air temperature (175°C). There was no significant effect (p