Structural and conformational modification of whey proteins induced by supercritical carbon dioxide

In this paper, the effect of supercritical carbon dioxide (SC-CO2) treatment on the structure and conformation of whey protein isolate (WPI) were investigated. The WPI solution treated with SC-CO2 at 20 MPa and 3060 C for 1 h showed that its turbidity and particle size were increased. The effect of SC-CO2 treatment at 60 degrees C on the fluorescence intensity of WPI was elevated indicating partial denaturation of its fractions and exposure of more hydrophobic regions. The secondary structure change of SC-CO2 treated WPI revealed a decrease in the a-helix content, hydrogen bonds and an increase in the amount of beta-sheet. A high shift of endothermic peak after SC-CO2 treatment was observed by the thermal analysis of WPI. These results confirmed that the structure and conformation of protein were modified with SC-CO2 treatment. Industrial relevance: There is a strong interest in the food industry in studying the modifying protein functionality to produce higher quality products. Supercritical carbon dioxide (SC-CO2) treatment described as green method has raised interests in its application for polymer modification. SC-CO2 is a unique processing method offering many advantages over conventional thermal processing methods, including the ability to retain the quality of food, which may be lost during conventional thermal processing. This work explores the SC-CO2 effect on the structural and conformational modification of protein which would be extremely helpful in understanding the improving of the protein functionalities such as, emulsifying and rheological properties in order to produce higher quality food products. (C) 2010 Elsevier Ltd. All rights reserved.