Munzur University, Faculty of Engineering, Food Engineering Department, Tunceli, Turkey.
Ege University, Faculty of Engineering, Food Engineering Department, İzmir, Turkey.
Ultrason Sonochem. 2019 Jun;54:135-141. doi: 10.1016/j.ultsonch.2019.02.006. Epub 2019 Feb 6.
In this study, the effect of the ultrasound and osmotic dehydration pretreatments before the convective drying of the persimmon fruit was assessed via their drying behavior and quality properties. Ultrasound-assisted osmotic dehydration (30 °C, 45 °Brix) was performed at 35 kHz for 10, 20, and 30 min. Afterward, samples were placed first in 45 then in 70 °Brix sucrose solutions; the solutions were next shaken at 100 rpm. The control group without ultrasound treatment dehydrated osmotically. The samples were dried in a tray drier at a temperature of 60 °C and an air velocity of 1.5 m/s. Ultrasound-assisted osmotic drying treatments increased water loss and sugar gain; moreover, the osmotic dehydration time was shorter than in the untreated group. The ultrasound-assisted osmotic dehydration demonstrated a significantly decreased drying time, increased drying rates, and a 21% increase in effective water diffusivity by 30 min. The ultrasound pretreated osmotic dehydration prior to hot air-drying decreased the total required drying time. The ultrasound-assisted osmotic dehydration affected the rehydration rate and total phenolic content significantly and there was no significant difference between the color change (ΔE, ΔC, and Hue°) of the ultrasound treatment (30 min) group and the untreated group.
本研究通过对柿子果实的干燥行为和品质特性的评估，考察了超声和渗透脱水预处理对其对流干燥的影响。在 35kHz 下进行超声辅助渗透脱水（30°C，45°Brix），时间为 10、20 和 30min。之后，将样品先放入 45°Brix 的蔗糖溶液中，然后放入 70°Brix 的蔗糖溶液中；溶液在 100rpm 下摇动。对照组未进行超声处理，进行渗透脱水。样品在温度为 60°C、空气流速为 1.5m/s 的托盘干燥器中干燥。超声辅助渗透干燥处理增加了水分损失和糖的获得；此外，渗透脱水时间短于未处理组。超声辅助渗透脱水使干燥时间显著缩短，干燥速率提高，有效水分扩散系数提高 21%，30min 时达到最大值。在热空气干燥之前进行超声预处理的渗透脱水可以减少总干燥时间。超声辅助渗透脱水对复水率和总酚含量有显著影响，超声处理（30min）组和未处理组之间的颜色变化（ΔE、ΔC 和 Hue°）没有显著差异。
