Grupo de Análisis y Simulación de Procesos Agroalimentarios, Departamento de Tecnología de Alimentos. Universidad Politécnica de Valencia, Camí de Vera s/n, Valencia, E46022 Spain.
J Sci Food Agric. 2011 Nov;91(14):2511-7. doi: 10.1002/jsfa.4344. Epub 2011 Mar 28.
The drying rate of vegetables is limited by internal moisture diffusion and convective transport mechanisms. The increase of drying air temperature leads to faster water mobility; however, it provokes quality loss in the product and presents a higher energy demand. Therefore, the search for new strategies to improve water mobility during convective drying constitutes a topic of relevant research. The aim of this work was to evaluate the use of power ultrasound to improve convective drying of potato and quantify the influence of the applied power in the water transport mechanisms.
Drying kinetics of potato cubes were increased by the ultrasonic application. The influence of power ultrasound was dependent on the ultrasonic power (from 0 to 37 kW m(-3) ), the higher the applied power, the faster the drying kinetic. The diffusion model considering external resistance to mass transfer provided a good fit of drying kinetics. From modelling, it was observed a proportional and significant (P < 0.05) influence of the applied ultrasonic power on the identified kinetic parameters: effective moisture diffusivity and mass transfer coefficient.
The ultrasonic application during drying represents an interesting alternative to traditional convective drying by shortening drying time, which may involve an energy saving concerning industrial applications. In addition, the ultrasonic effect in the water transport is based on mechanical phenomena with a low heating capacity, which is highly relevant for drying heat sensitive materials and also for obtaining high-quality dry products.
蔬菜的干燥速率受到内部水分扩散和对流传输机制的限制。干燥空气温度的升高会导致水分更快地移动；然而，这会导致产品质量损失，并需要更高的能源需求。因此，寻找新的策略来提高对流干燥过程中的水分迁移能力是一个具有重要研究意义的课题。本工作旨在评估在马铃薯的对流干燥中应用功率超声以提高水分迁移能力，并量化所施加功率对水分传输机制的影响。
超声应用可以提高马铃薯块的干燥动力学。超声功率（0 至 37kW/m3）对功率超声的影响取决于超声功率，施加的功率越高，干燥动力学越快。考虑到外部传质阻力的扩散模型很好地拟合了干燥动力学。通过模型拟合，可以观察到施加的超声功率对识别出的动力学参数（有效水分扩散系数和传质系数）具有比例且显著（P<0.05）的影响。
在干燥过程中应用超声代表了一种比传统对流干燥更有趣的替代方法，通过缩短干燥时间，可以节省工业应用中的能源。此外，超声对水分传输的影响基于机械现象，其加热能力低，这对于干燥热敏性材料以及获得高质量的干燥产品非常重要。
