Abstract

The aim of the study was to determine the effect of ultrasound power on some selected quality parameters of yogurt drink produced with thermosonicated milk. Ultrasonication treatments for raw milk samples preheated to 70C were carried out at different ultrasound powers (100, 125 and 150W). Yogurt drinks were produced with milk samples processed with thermosonication or conventional heating (10 min at 90C). Thermosonication treatment did not influence proximate composition and color properties of samples; however, it decreased serum separation values significantly while increasing apparent viscosity values at higher ultrasound power. Rheological measurements indicated that all yogurt drink samples exhibited a non-Newtonian behavior. In conclusion, thermosonication treatment could be successfully used in the production of yoghurt drink and improve its major quality parameters such as delayed serum separation and increased apparent viscosity.

Key words: Serum separation; Thermosonication; Ultrasound; Viscosity; Yoghurt drink