为探究超声及超声渗透预处理对桃片水分迁移及红外辐射干燥特性的影响，经超声及超声渗透30、60 min预处理后，进行红外辐射80 ℃干燥处理，采用低场核磁共振技术测定预处理后桃片横向弛豫时间T2图谱，分析水分状态及分布变化，得到干燥特性曲线，并分析水分状态及分布对干燥特性的影响。结果表明，超声降低桃片固形物含量，超声渗透明显增加固形物含量并降低水分含量；不同预处理均改变桃片内部水分状态和分布。超声后，桃片不易流动水和自由水弛豫时间增加，水分自由度增加，从而提高干燥速率，增加水分有效扩散系数；超声渗透后，桃片结合水、不易流动水及自由水弛豫时间均减小，且自由水含量明显降低，而不易流动水及结合水含量相对升高，从而降低干燥速率，减小水分有效扩散系数。该研究为超声及超声渗透预处理对红外辐射干燥水分扩散研究提供参考。

To explore the effect of ultrasound (UL) and ultrasound-assisted osmotic dehydration (ULOD) pretreatments on water transfer in peach slices and the drying characteristics of infrared radiation drying, samples were pretreated with UL and ULOD for different time followed by infrared radiation drying at 80 ℃. Low-field nuclear magnetic resonance (LF-NMR) was used to measure the transverse relaxation times (T2) of the pretreated peach slices. Changes in water status and distribution were analyzed, the drying characteristics curve was obtained, and the effects of water status and distribution on the drying characteristics were explored. The results showed that UL decreased the soluble solid content, and ULOD significantly improved the soluble solid content and decreased the water content. Both pretreatments affected the water status and distribution. UL increased the transverse relaxation times of immobilized water (T22) and free water (T23), indicating that the degree of freedom of water increased. As a result, UL enhanced the drying rate and increased the water effective diffusion coefficient (Deff). ULOD decreased the transverse relaxation time of bound water (T21), immobilized water (T22), and free water (T23). The free water content was significantly reduced, and the immobilized water and bound water content increased relatively, thus reducing the drying rate and decreasing the Deff of infrared radiation drying. This study provides the theoretical basis for the study of the effects of UL and ULOD pretreatments on water transfer and diffusion characteristics of fruite slice treated by infrared radiation drying.

公益性行业（农业）科研专项（201503142）