The aim of this study was to examine the effect of high-power ultrasound (US) and highpressure processing (HP) on model systems composed of whey protein concentrate (WPC) and whey protein isolate (WPI) with or without guar gum addition. This kind of systems can be found in food production industry so the aim was to use novel food processing technologies to be utilized as a method for products development. Aqueous suspensions (10 g kg-1) of powdered whey proteins were treated with either ultrasound or high pressure. The treatment conditions were as follows: US: frequency of 30 kHz, for 5 and 10 min ; HP: pressure intensity 300-600 MPa, for 5 and 10 min. Rheological and thermophysical properties were analyzed after guar gum addition (0.5 g kg-1). Ultrasound treatment showed a significant influence on all examined properties through protein denaturation caused by cavitation and microstreaming effects. High pressure caused significant increase in viscosity and consistency coefficients of model systems with and without guar addition. Significant decrease of initial freezing and initial thawing temperature was observed in all samples. With this research the direct influence of ultrasound and high-pressure treatment on the rheological and thermophysical properties of whey protein isolate and concentrate model systems with or without guar gum was demonstrated.

Food processing technology