不同干燥温度对牛肉脯水分分布迁移规律的影响

Effect of Different Drying Temperatures on Moisture Distribution and Migration of Dried Beef Jerky

摘要:

借助低场核磁共振技术及其核磁共振成像技术，探讨不同热风干燥温度（50～70 ℃）在干燥时间（120～180 min）范围内牛肉脯的水分状态、水分质量分数与水分分布情况。3种干燥温度下平均干燥速率分别为 0.226 5、0.277 9、0.353 9 g/（g·min）；牛肉脯的干燥效果主要取决于其不易流动水的含量，通过在热风干燥过程中提高温度，可以明显提高肉脯的干燥速率，结合水、不易流动水和自由水的迁移也会加快；干燥过程中不易流动水在自由水和结合水之后发生变化，不同热风温度条件下的峰面积、峰比例变化趋势较为一致，温度越高曲线变化愈明显；牛肉脯水分含量与峰面积之间呈现良好的线性关系，其中70℃干燥的线性回归方程为 y=323.34x- 6 092.77（R²=0.975 0）；纵向弛豫时间T1加权成像图表明牛肉脯70 ℃热风干燥过程中氢质子密度分布相对均匀，干燥品质较高。比较3种干燥温度的差异，这可为今后肉脯品质提升、产品研发和节约能源提供理论依据。

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.