Characterization of high pressure jet-induced fat-protein complexation

Area of Science:

• Food Science
• Dairy Science
• Protein Chemistry

Background:

• High-pressure-jet (HPJ) processing is known to affect dairy system structures.
• HPJ treatment can disrupt fat droplets and casein micelles, promoting fat-protein interactions.

Purpose of the Study:

• To elucidate the fat-casein association induced by HPJ processing in a model milk system.
• To characterize the physical states and structural changes of fat and protein after HPJ treatment.

Main Methods:

• Model milk formulation (confectionary fat, micellar casein, water).
• High-pressure-jet (HPJ) treatment (400 MPa) and control (non-HPJ).
• Ultracentrifugation, Differential Scanning Calorimetry (DSC), Time-Domain Nuclear Magnetic Resonance (TD-NMR), Cryogenic Transmission Electron Microscopy (Cryo-TEM).

Main Results:

• HPJ treatment caused fat to precipitate with protein, unlike control milk where fat creamed.
• DSC and TD-NMR revealed an additional, less stable fat crystalline state in HPJ-treated milk.
• Cryo-TEM showed HPJ treatment resulted in porous protein aggregates with dispersed fat, indicating entrapment.

Conclusions:

• HPJ processing induces a robust association between fat and casein proteins in model milk.
• This association leads to fat entrapment within casein aggregates, altering fat crystallization behavior.
• The observed fat-protein association is largely independent of casein charge.