Lipid phase behavior governs microstructural retention and sustained α-tocopherol release in pullulan composite films...

Area of Science:

• Food Science and Technology
• Materials Science
• Chemical Engineering

Background:

• Entrapping lipophilic bioactives in hydrophilic matrices causes phase separation and uncontrolled release.
• Controlling lipid phase behavior is key to managing nanoemulsion microstructure and bioactive release.

Purpose of the Study:

• To investigate how tuning lipid phase behavior affects the microstructure of alpha-tocopherol-loaded nanoemulsions and pullulan films.
• To develop stable active packaging systems for extending the shelf life of lipid-rich foods.

Main Methods:

• Formulation of nanoemulsions with varying coconut oil content (40% and 60%).
• Characterization of nanoemulsion properties (droplet size, polydispersity index, interfacial tension, critical micelle concentration).
• Fabrication and mechanical/barrier property testing of derived pullulan films.
• Kinetic modeling of alpha-tocopherol release and application testing on walnut kernels.

Main Results:

• 40% coconut oil led to stable nanodroplets (18.59 nm) with reduced interfacial tension and CMC.
• 60% coconut oil resulted in a homogeneous architecture in films with high tensile strength (26.51 MPa) and low oxygen/water vapor permeability.
• Films exhibited quasi-Fickian diffusion, restricting alpha-tocopherol release (88.88% retention) and preserving walnut quality.

Conclusions:

• Regulating internal lipid phase behavior offers a predictable microstructural framework for active packaging.
• This approach effectively controls bioactive release and enhances the shelf life of lipid-rich foods.
• The developed active packaging system shows significant potential for food preservation applications.