超声辅助糖液渗透处理对真空冷冻干燥桃脆片干制品品质及吸湿性的影响

为探究超声辅助糖液渗透处理对真空冷冻干燥桃脆片干制品品质及吸湿性的影响，本实验比较了白桃经4 种糖液（蔗糖、麦芽糖、葡萄糖、低聚异麦芽糖）超声辅助渗透处理后桃片的水分损失率、固形物增加率以及真空冷冻干燥后桃脆片的微观结构、质构特性（硬度、脆度）、吸湿性及玻璃化转变温度。结果表明：与对照组相比，经超声辅助糖液渗透处理的桃片水分损失率、固形物增加率提升，孔隙更加致密且细胞组织发生破裂和结构坍塌，硬度显著提高（P＜0.05）；且超声辅助糖液渗透处理可以降低桃脆片的吸湿性，在相对湿度从0梯度增加到90%的过程中，各处理组样品最终达到吸湿平衡时的质量变化率范围为55.16%～59.63%，对照组为61.43%；与对照组玻璃化转变温度（52.37 ℃）相比，超声辅助麦芽糖渗透脱水处理使桃脆片体系的玻璃化转变温度升高到64.27 ℃。综上，超声辅助糖液渗透处理对桃脆片品质产生影响的同时，也对降低桃脆片吸湿性和改变桃脆片体系玻璃化转变温度具有重要影响，本研究可为改善和提升白桃干制品品质提供技术参考。

Effect of Ultrasonic-Assisted Sugar Osmotic Pretreatment on Quality and Hygroscopicity of Vacuum Freeze-Dried Peach Chips

To investigate the effects of ultrasound-assisted sugar pretreatment on the quality and hygroscopicity of vacuum freeze-dried peach chips, we compared the moisture loss rate and solid yield of peach slices after ultrasound-assisted osmosis in four sugar solutions (sucrose, maltose, glucose and oligoisomaltose) as well as the microstructure, texture (hardness and brittleness), hygroscopicity and glass transition temperature of the resultant peach chips. The results showed that ultrasound-assisted osmosis increased the water loss rate and solid gain of peach slices, resulted in denser pores, cell rupture and structural collapse, and significantly increased the hardness of peach chips compared to the control group (P < 0.05). In addition, ultrasound-assisted osmosis reduced the hygroscopicity of peach chips, and the percentages of mass change after reaching the hygroscopic equilibrium with increasing relative humidity from 0 to 90% ranged from 55.16% to 59.63%, compared to 61.43% for the control group. Ultrasound-assisted osmosis increased the glass transition temperature to 64.27 ℃ compared to the control group (52.37 ℃). In conclusion, ultrasonic-assisted osmotic treatments with sugar solutions have significant influence on the product quality while reducing the hygroscopicity and changing the glass transition temperature of peach chips. The results of this study provide a technical reference for improving the quality of dried peach chips.