Study On The Mass Transfer Of Osmotic Dehydration Enhanced By Acoustic Cavitation

Osmotic dehydration is that under certain temperature the fresh material is immersed into the high osmolarity solution, using different membrane osmotic pressure on both sides to remove some of the material's moisture. Duing to the slowness of the osmotic dehydration processes, to enhance the mass transfer of the process makes the scholars' a keen interest. Enhancing osmotic dehydration with acoustic cavitation enhances the rate of dehydration greatly, and after dehydration the sensory quality of products is almost the same as fresh material. So the technology of enhancing mass transfer with acoustic cavitation as the third generation active intensification mass transfer technology has the broad development prospects.In this paper, the mass transfer of osmotic dehydration process is studied as potatoes, carrots used as raw materials.The study shows that the potato,carrot of osmotic dehydration is notably enhanced by acoustic cavitation.In the solid-liquid systems of potato-NaCl, the dehydration rate of material increases with the increase of cavitating intensity,the time of acoustic cavitation,the concentration and temperature of the infiltration solution, and internal resistance increases with the increase of materials thickness, the dehydration rate decrease; That solid gain rate increases with the increase of the time of acoustic cavitation,the concentration and temperature of the infiltration solution, and with the increase of cavitating intensity, solid gain rate increases after decreases. So the best work condition: When output current intensity of supersonic signal generator is 0.5A% the time of acoustic cavitation is 30min,the concentration of the infiltration solution is 15%,temperature of the infiltration solution is among 30～40°C, materials thickness is about 4～5mm, That the dehydration rate can reach 17%, and the solid gain rate is about 5%.In the solid-liquid systems of Carrot-sucrose, Impact of the time of osmotic dehydration,the concentration and temperature of the infiltration solution on the osmotic dehydration of carrot were researched. The results shows that as the time of acoustic cavitation, the concentration and temperature of the infiltration solution increase, the dehydration rate and the solid gain rate of carrot increases. Through the results of the experiment, the dehydration rate constant,equilibrium dehydration rate and the mathematical model of dehydration rate be ascertained. Calculated dehydration rate using mathematical model of the dehydration rate and the experimental result are in good agreement.