High Pressure Jet Processing for Clean-Label Foods and Ingredients

High Pressure Jet (HPJ) is a nonthermal technology that promotes novel functionality by subjecting liquid foods to hydrostatic pressure (up to 500 MPa), high shear (speeds up to Mach 4) and impingement. A liquid is pressurized by an intensifier pump and then a restriction to flow (diamond nozzle) creates an aerosol that is immediately recovered in a tube-in tube heat exchanger. Experiments conducted in liquid milk, demonstrated that extensive casein micelle dissociation occurs at processing pressure >350 MPa resulting in increased viscosity (3.9 mPa.s vs. 1.2 mPa.s in control), foaming (foam expansion index, FEI= 116% vs. 63% in controls) and emulsifying (emulsion activity index, EAI=8.3% vs. 6.1% in controls) of both skim and whole milk. Additionally, ultracentrifugation studies showed a strong interaction between milk fat triglycerides and casein proteins, resulting in co-precipitation of protein and fat after HPJ processing. In a different configuration, the HPJ was connected to a modified spray dryer (SD) for the direct drying of HPJ processed liquid streams. The reconstituted powders showed improved foaming (FEI=114% vs. 60% in controls) and emulsifying (ESI=148% vs. 134%) properties indicating that the transformation to powder ingredients did not negatively affect the observed functionality. In further experiments, protein-protein and protein-fat interactions allowed for the stabilization of a protein-rich, carrageenan-free, HPJ chocolate milk for 14 day without appreciable phase separation. The use of HPJ also showed potential for the stabilization of plant proteins (e.g., soy protein) in liquid foods, and the formation of stable foams in concentrated protein systems (e.g., ice cream). HPJ technology has a strong potential as a processing operation for the development of novel clean label foods and food ingredients.