本文以苹果为原料，为提高热风干燥速率，改善产品品质，通过研究不同功率下（0、160、320、480 W）超声和羧甲基纤维素涂膜复合预处理对苹果片热风干燥特性（干基含水量和干燥速率）及产品品质（总酚、颜色、DPPH清除率、复水比、微观结构）的影响，为其它产品干燥提供研究依据。在60~90 ℃干燥条件下，苹果片的干燥速率、总酚含量、DPPH清除率、复水比均随着超声功率增大而增大，干燥时间、色差随超声功率增大而减少。在70 ℃、480 W条件下，可获得较高的干燥速率和较好的干燥品质，干燥时间为150 min，总酚含量为16.25 mg GAE/g DW，色差值ΔE为8.13，DPPH清除率为38.15%，复水比达5.23，用电子显微镜对苹果干制品进行观察微观结构，可以发现经超声处理后的干制品内部的褶皱多、微孔通道较多。综上，涂膜-超声复合预处理能够缩短干燥时间，提高干燥速率，提高产品的总酚含量、DPPH清除率和复水比，改善干制品色泽。

The experiment used apples as materials, in order to improve the hot air drying rate and quality of dried products. In this paper, carboxymethyl cellulose (CMC) coating film and pretreatment with different ultrasonic powers (0, 160, 320, 480 W) were used to study the hot air drying characteristic curve (water content of dry base and drying rate) and quality (total polyphenol and color difference, DPPH removal rate, rehydration rate and dried microstructure) of apple slices. Under the drying condition of 60~90 ℃, the increase of ultrasonic power led to the increases of drying rate, total polyphenol, DPPH removal rate and the rehydration ratio, while the drying time and color difference(ΔE) decreased with the increase of ultrasonic power. At 70 ℃ and 480 W, a higher drying rate and better drying quality could be obtained, the drying time of drying apple slices is 150 min, the total phenol content is 16.25 mg GAE /g DW, the ΔE is 8.13, the DPPH scavenging rate is 38.15%, and the rehydration ratio is 5.26. The microstructure of dried apple products after ultrasonic pretreatment could be observed by using an electron microscope, and it could be found that there are many folds and microspore channels. Overall, the combined application of ultrasonic and CMC coating pretreatments could shorten the drying time, improve the drying rate and total polyphenol content, DPPH scavenging rate, rehydration ratio of the products, and strengthen the quality of the dried apple slices.

河北省自然科学基金项目（C2019208315）；河北省农林科学院创新工程项目（2019-2-1）