Some thermodynamic considerations in food formulation

Several factors underlie the thermodynamic similarity of foods. First is the common physiological storage function of most important components of food raw materials. Second is the general character of non-specific intermolecular interactions of food macromolecules. Third is the mimicry of biopolymers that underlie quite similar physico-chemical properties of biopolymer species. Molecular mimicry and molecular symbiosis affect phase behaviour and rheology of biopolymer mixtures. Molecular mimicry implies the chemical and structural similarity of hydrophilic surfaces of globular proteins with their chemical information hidden in the hydrophobic interior, and the low excluded volume of the globules. Another mimicry technique is the binding of different biopolymers into a new hybrid (e.g. conjugates) macromolecule acquiring an affinity to the macromolecular constituents as co-solutes. Molecular symbiosis means that interactions (attraction or repulsion) between biopolymer molecules greatly differing in conformation (globular and rod-like), favour the biological efficiency of one of them, at least. Thermodynamic incompatibility is typical of food macromolecules, whose denaturation, association, complexing and chemical modification reduce their mimicry and co-solubility. Biopolymer incompatibility, self-association and interbiopolymer complexing contribute to synergistic and antagonistic effects of food formulation. The thermodynamic approach is highly promising for modelling of food formulation. Food formulation aims to control interactions between proteins,. polysaccharides and their interactions with other food components. Thermodynamic aspects of food digestion mechanisms and the multifunctionality of exopolysaccharides, prebiotics, storage proteins and other chyme components are considered in terms of food formulation. Normally, food and chyme are phase-separated systems. Thermodynamic similarity, which is a fundamental feature of processed food systems determines the high efficiency of empirically developed food technologies and the low sensitivity of structural and mechanical properties of the chyme to the composition of diets. (C) 2002 Elsevier Science Ltd. All rights reserved.