Learning objectives
The aims of the course are the following: <br />
1. to show that thermodynamics is the foundation for understanding the main machinery related to food preservation; <br />
2. to give an outline of colloidal chemistry, foundation of structural and functional features of foods. <br />
Prerequisites
No preliminary examinations are requested.
Course unit content
1. Survey of Classical Thermodynamics. The concept of activity: water activity and food preservation. <br />
2. Changes of state: Phase equilibria in pure compounds and in binary systems. Phase transition in food materials. The glassy state and the glass transition. <br />
3. Non-equilibrium thermodynamics and transport processes. Order out of caos. Force and flow. Phenomenological equations. Theorems. Onsager law. Dissipation function. Steady state concept. Mobility of the ions in solution. Electrophoresis. Diffusion. Sedimentation. Viscosity. <br />
4. Food Colloids. Dispersed systems. Size and shape of colloidal particles. Ostwald classification. Surface tension and surface free energy. Van de Waals forces. Lennard-Jones potential. Intermolecular forces in colloidal systems. DLVO theory. Hydrophobic interactions, hydrophobic hydration and Hydrophobic effect : model for the interpretation. Structure and classification of surfactants. Micelle formation. Casein Micelles. Emulsifiers and stabilizers in foods. Cohesion and adhesion work, spreading coefficient, wettability. Ostwald ripening. Gibbs isotherm. Laplace pressure. The most common food colloids: Emulsions, foams, dispersions and suspensions, gels. Methods of preparation. Examples: beer, whipped cream, ice-cream, meringue, butter, mayonnaise. Marangoni effect. Physico-chemical properties of a food colloid. Micro-emulsions. Lyotropic and thermotropic liquid crystals. <br />
Full programme
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Bibliography
- Pieter Walstra, Physical Chemistry of Foods, Marcel Dekker, Inc, New York (2003) <br />
- Eric Dickinson, An Introduction to Food Colloids, Oxford Science Publications (1992) <br />
Teaching methods
Lectures by means of computer presentations, available to the students before classes. <br />
Written examinations on the whole syllabus during normal examination sections. <br />
Assessment methods and criteria
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Other information
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