Effect of Ultrasound Treatment on Structural Properties and Gel Water Holding Capacity of Transglutaminase-Catalyzed Whey Protein Isolate

The effect of ultrasound treatment (20 kHz,400 W,0,10,20,30,40 min) on the molecular weight distribution,particle size distribution,fluorescence intensity,surface hydrophobicity and water holding capacity (WHC) of TGase-catalyzed WPI were studied. SDS-PAGE indicated that the formation of high molecular aggregates (with a molecular weight about 120 kDa) after the reaction of TGase cross-linking,and the amount of aggregates increased with the increase of ultrasound time. The results of fluorescence spectroscopy and surface hydrophobicity analysis showed that TGase-catalyzed WPI had higher fluorescence intensity and surface hydrophobicity than WPI,which increased with the ultrasound time increasing. Besides,the particle size of TGase-catalyzed WPI was significantly higher than that of WPI. In addition,the water holding capacity of WPI increased after TGase cross-linking,which also increased with the increase of ultrasound time. Therefore,TGase-catalyzed cross-linking of WPI could change WPI structure,and enhance its gel water holding capacity.