Effect of ultrasonic treatment on rheological and emulsifying properties of sugar beet pectin.

The effects of ultrasonic treatment on rheological and emulsifying properties of sugar beet pectin were studied. Results indicated that intrinsic viscosity ([eta]) and viscosity average molecular weight ([M-v]) decreased with the increased time from 0 to 30 min but increased when the duration prolonged to 45 min. The change of apparent viscosity with shear rate of all pectin solutions could be well described by Sisko model (R-2 >= .996) and the infinite-rate viscosity (eta(infinity)) and the consistency coefficient (k(s)) values decreased after ultrasonic treatment. Ultrasonic treatment could have an effect on dynamic moduli and activation energy of sugar beet pectin solutions. Particle size of pectin emulsions decreased and absolute zeta potential increased with increased time from 0 to 20 min. Excessive ultrasonic duration (30 and 45 min) could result in the aggregation of oil droplets in pectin emulsion and decrease in emulsifying stability. It could be concluded that ultrasonic treatment could affect the rheological and emulsifying properties of sugar beet pectin. The results have important implications for understanding the ultrasonic modification of sugar beet pectin.