Sequential ultrasound and transglutaminase treatments improve functional, rheological, and textural properties of whey protein concentrate

In this study, the combined effect of ultrasound pretreatment (US) and microbial transglutaminase (MTG) on the rheological, textural, and functional attributes of whey protein concentrate (WPC) were investigated. All the samples exhibited non-Newtonian shear-thinning behavior. Treatment with US lead to a significant increase in foaming capacity, gel hardness, and adhesiveness at 7.5 min, while reduced emulsifying capacity and syneresis at all levels. Moreover, consistency coefficient, foam stability, emulsifying capacity, emulsion stability, gel hardness and adhesiveness improved, whereas a slight decrease was observed in foaming capacity and syneresis of gels as a consequence of TG treatment respectively. 5 min US - 5 U.g(-1) pr TG treated sample exhibited the least syneresis value of all samples. SEM images affirmed the beneficial effects of treatments on texture, reduction of voids size and supported the textural results. Overall, ongoing US pretreatment and TG treatment were successful in modifying the functional properties of whey proteins. Industrial relevance: Food industry is consuming whey proteins for their functional characteristics besides their nutritional value. Microbial transglutaminase (MTG) can modify whey protein structure. High intensity ultrasound (HIU) is also mentioned as a material-altering technology. Heat denaturation is used for changing whey protein structure before enzyme treatment. The purpose of this study was to investigate the feasibility of replacing heat denaturation by ultrasound treatment before transglutaminase addition to a whey protein system. We also aimed to test the simultaneous effect of US and TG in order to meet emerging demands and produce different novel targeted products. Our results indicated that US treatment may replace heat denaturation before TG treatment and combination of these two factors improved various properties of whey protein systems.