Mierzwa Dominik, Kowalski Stefan Jan, Kroehnke Joanna
Poznań University of Technology, Department of Process Engineering, Institute of Technology and Chemical Engineering, ul. Berdychowo 4, PL-60-965 Poznań, Poland.
Food Technol Biotechnol. 2017 Jun;55(2):197-205. doi: 10.17113/ftb.55.02.17.4942.
In this paper the kinetics of osmotic dehydration of carrot and the influence of this pretreatment on the post-drying processes and the quality of obtained products are analysed. Osmotic dehydration was carried out in the aqueous fructose solution in two different ways: with and without ultrasound assistance. In the first part of the research, the kinetics of osmotic dehydration was analysed on the basis of osmotic dewatering rate, water loss and solid gain. Next, the effective time of dehydration was determined and in the second part of research samples were initially dehydrated for 30 min and dried. Five different procedures of drying were established on the grounds of convective method enhanced with microwave and infrared radiation. The influence of osmotic dehydration on the drying kinetics and final product quality was analysed. It was found that it did not influence the drying kinetics significantly but positively affected the final product quality. Negligible influence on the drying kinetics was attributed to solid uptake, which may block the pores, hindering heat and mass transfer. It was also concluded that the application of microwave and/or infrared radiation during convective drying significantly influenced the kinetics of the final stage of drying. A proper combination of aforementioned techniques of hybrid drying allows reducing the drying time. Differences between the particular dehydration methods and drying schedules were discussed.
本文分析了胡萝卜的渗透脱水动力学以及这种预处理对干燥后过程和所得产品质量的影响。渗透脱水在果糖水溶液中以两种不同方式进行：有超声辅助和无超声辅助。在研究的第一部分，基于渗透脱水速率、水分损失和固形物增加来分析渗透脱水动力学。接下来，确定脱水的有效时间，并且在研究的第二部分中，样品先脱水30分钟然后进行干燥。基于对流方法并增强微波和红外辐射建立了五种不同的干燥程序。分析了渗透脱水对干燥动力学和最终产品质量的影响。发现它对干燥动力学没有显著影响，但对最终产品质量有积极影响。对干燥动力学的影响可忽略不计归因于固形物吸收，这可能会堵塞孔隙，阻碍传热和传质。还得出结论，在对流干燥过程中应用微波和/或红外辐射显著影响干燥最后阶段的动力学。上述混合干燥技术的适当组合可以减少干燥时间。讨论了特定脱水方法和干燥方案之间的差异。
