Abstract:The moisture status, moisture content and moisture distribution of beef jerky at different hot air-drying temperatures (50~70 ℃) within drying time (120~180 min) were investigated by low-field nuclear magnetic resonance and its nuclear magnetic resonance imaging technology. Results: The average drying rates at three drying temperatures were 0.226 5, 0.277 9, and 0.353 9 g/(g·min), and the drying effect of beef jerky mainly depended on its non-flowing water content. The drying rate of dried meat could be significantly increased by increasing the temperature during the hot-air drying process, and the migration of bound water, non-flowing water and free water could also be accelerated. During the drying process, the non-flowing water changed after the combination of free water and bound water. The changing trend of peak area and peak proportion under different hot air temperatures was consistent, and more significant curve changes could be observed under higher temperature. There was a good linear relationship between the moisture content of beef jerky and the peak area, and the linear regression equation of drying at 70 ℃ was y=323.34x- 6 092.77（R2=0.975 0). The T1-weighted image of longitudinal relaxation time showed that the hydrogen proton density distribution was relatively uniform and the drying quality was better during the drying of beef jerky at 70 ℃. The difference comparison of three drying temperatures could provide a theoretical basis for the improvement of jerky quality, product development and energy saving in the future.
