Effects of ozone processing on chemical, structural and functional properties of whey protein isolate

High concentration of gaseous ozone was used to treat whey protein isolate (WPI) powder for different times ranging from 30 to 480 min. The aim of the present work was to study the changes in protein structure and evaluate their consequences on selected functional properties. Surface hydrophobicity, free sulphhydryl groups, turbidity, FTIR, SDS-PAGE, HPLC analysis are performed to evaluate the chemical and structural effects of ozone. The effect of ozonation on the solubility and the foaming properties of proteins are also determined. Results show a reduction of free sulphhydryl groups and an increase of surface hydrophobicity, indicating a self-rearrangement in the protein structure following ozonation. Thus, ozonation allows creation of a more flexible structure without formation of a strong network of disulphide bond or aggregations, which is corroborated by the turbidity analysis and SDS-PAGE. Ozone processing induces modifications that improve the foaming capacity and foam stability, however, a slight reduction in the solubility is encountered.