Can protein functionalities be enhanced by high-pressure homogenization? - A study on functional properties of lupin proteins

Many common foods like salad dressings or milk products are processed by high-pressure homogenization. Compared to conventional treatments, dynamic high pressures have been found to induce significant changes in the protein layer at the interface of these emulsions. But until now the influence of high-pressure homogenization on the functionality of proteins itself has only been scarcely studied. The aim of this study was to characterize the influences of high-pressure homogenization on the functional properties of lupin proteins of different lupin species because these proteins exhibit good functionality and can be applied as natural emulsifiers in food systems. Especially, the influences on the emulsifying and gelling properties of lupin proteins were studied. The gel strength and the emulsifying capacities of L. albus proteins were increased significantly after high-pressure homogenization with pressures up to 150 MPa at 35 and 60 °C, respectively. The protein solubilities were only barely influenced by homogenization. Completely different results were obtained for L. angustifolius proteins. The emulsifying properties could not be enhanced by high pressure homogenization, which might be due to the presence of different protein fractions in protein isolates of these two species. These results imply that high-pressure homogenization has interesting potential for enhancing functional properties of lupin proteins of L. albus L., while the functional properties of L. angustifolius proteins after homogenization remained similar. High-pressure homogenization is therefore likely to be a tool for enhancing protein functionality, especially for proteins having inferior functionality due to heat treatment or prior processing.