Impact of Ultrasound Intensity and Duration on the Rheological Behaviour of Sodium Alginate Solution

Abstract

One of the recent uses of sonication is to change the composition and structural properties of hydrocolloids. This study aimed to examine the impacts of sonication at different intensities (0, 75, and 150 W) and time (0, 5, 10, 15, and 20 min) on the viscosity and rheological properties of sodium alginate solution. The results showed that the apparent viscosity of sodium alginate solution (control sample) decreased from 0.075 to 0.032 Pa.s with increasing shear rate from 12.2 to 134.5 s-1. Also, the apparent viscosity of sodium alginate solution decreased from 0.044 to 0.019 Pa.s with enhancing the sonication time from 0 to 20 min (shear rate=61 s-1, 150 W). Various rheological equations (Power law, Bingham, Herschel-Bulkley, Casson, and Vocadlo) were employed to fit the empirical values, and the results confirmed that the Power law model was the best fit to describe the flow behaviour of sodium alginate solution. The consistency coefficient of sodium alginate solution significantly decreased from 0.216 Pa.sn to 0.151 Pa.sn (p<0.05) with enhancing sonication time from 0 to 20 min. Furthermore, the consistency coefficient of sodium alginate solution decreased significantly (p<0.05) while the ultrasonic power enhanced. Flow behaviour index of sodium alginate solution enhanced significantly (p<0.05) while the intensity and duration of ultrasound treatment enhanced.

Keywords

• consistency coefficient
• flow behaviour index
• rheological models
• ultrasound