The Effect of Ultrasound on the Rheological Properties of Apple Juice

In this paper, the effect of ultrasonic treatment on the rheological properties of apple juice (Idared variety) was studied. The juice was treated with ultrasonic waves for 5 and 10 minutes relative to the untreated sample. The tests were conducted using rotational viscometer at shear rates ranging from 40 to 140 s-1 at constant temperature of 20oC. There was no influence of ultrasonic treatment on the rheological character of apple juice. The rheological behaviour of untreated apple juice had the characteristics of non-Newtonian fluids. The value of the flow index was less than 1, indicating its pseudoplastic character. Because the ultrasonic treatment doesn’t change the structural properties it can be used for mild preservation of apple juice. This technology of juice processing allows to reduce the energy consumption, what contributes to the rational management of energy resources.