Zein encapsulation of amphiphilic compounds

Functional compounds including flavors, essential oils, antioxidants or nutraceuticals are widely added into food system to enhance sensory properties or for health purposes. However, these compounds might not be stable in food systems during processing, storage and food preparation. Encapsulation has been proposed as a practical approach to stabilize these compounds and control their release. Zein is an amphiphilic protein originally obtained from corn. Its film-forming and coating ability make it potentially useful as a wall material for encapsulation. Amphiphilic compounds have been recognized to form well defined microspheres by evaporation induced self-assembly (EISA) in binary solvents, which is useful in encapsulation. The goals of this research were to improve our understanding of the development of zein encapsulation structures. The main objective was to investigate the effect of the hydrophobicity of core materials as measured by contact angle on the formation and structure of zein encapsulates obtained by evaporation induced self-assembly of ethanol-water systems. A second objective was to apply the knowledge learned in the above objective to propose a strategy to capture and encapsulate flavors generated in frying oils. Results showed that citral was effectively encapsulated with zein. Zein encapsulation morphology was related to the droplet formation ability of core materials in ethanol-water systems. Amphiphilic compounds were believed to form stable droplets in ethanol-water, which favored zein encapsulation. Hydrophobic compounds showed phase separation in ethanol-water which led to the formation of films rather than closed structures. A model system consisting of mixtures of a flavor and a hydrophobic carrier was used to study the effect of carriers on encapsulation ability of zein by the self-assembly process. The presence of the carrier negatively affected encapsulation effectiveness. Citral was recovered from the flavor-carrier mixture by extraction and phase separation at sub-freezing temperatures. Recovered citral was effectively encapsulated by zein. Fried chips flavors were also recovered from frying oil and encapsulated in zein by ethanol extraction and phase separation at low temperatures. Sensory ranking test was used to confirm the presence of recovered flavors after zein encapsulation