Dynamics of heat transfer and moisture in beef jerky during hot air drying.

The aim of this study was to investigate the surface temperature, moisture migration, muscle shrinkage and microstructure of beef jerky during hot air multi-stage drying. Temperatures were sequentially increased from 40 to 50 to 60 °C, and corresponding times were 0.5 h - 1 h - 2.5 h, 0.5 h - 2 h - 1.5 h, 1 h - 1 h - 2 h and 1 h - 2 h - 1 h in 4 groups. With increasing temperature, moisture content and diffusivity of the sample decreased, the surface temperature, moisture migration, muscle shrinkage and the gaps (spacing) between muscle fibres increased. The jerky in groups 3 and 4 attained high overall acceptability. The jerky dried at 40 °C for 1 h, 50 °C for 1 h and 60 °C for 2 h had highest quality. The results cover the range of temperature and time used in beef drying and can be used to optimize the drying process of beef.