Thermodynamic Aspects of Biopolymer Functionality in Biological Systems, Foods, and Beverages

Abstract

Molecular mimicry and molecular symbiosis are proposed to be the main factors controlling thermodynamic activity and phase behavior of macromolecular compounds in foods, beverages, and chyme. Molecular mimicry implies a chemical resemblance of hydrophilic surfaces of globular proteins with their chemical information hidden in the hydrophobic interior and low excluded volume of the globules. The molecular mimicry contributes to the efficiency of enzymes. Molecular symbiosis means that interactions attraction or repulsion) between biopolymer molecules greatly differing in conformation (globular and rod-like) favor the biological efficiency of one of them at least. The symbiosis is based on excluded volume effects of macromolecules in mixed solutions. Association-dissociation of rod-like macromolecules can dictate thermodynamic activity of an enzyme in the mixed solution. Thermodynamic incompatibility is typical of food macromolecules, whose denaturation, association, complexing, and chemical modification reduce their mimicry and co-solubility. Foods are normally phase-separated systems with highly volume-occupied phases. The phase-separated nature of the gel-like chyme is important to the efficiency of digestion of mixed diets. Phase separation of biopolymer mixtures, presumably, underlies mechanisms of nonspecific immune defense. The phase behavior-functionality relationships is presented through concrete examples of some foods (such as milk products, low-fat spreads, ice cream, wheat and rye doughs, thermoplastic extrudates, etc.), beverages (tea and coffee), and chyme.

Investigation of particle dynamics in gels involving casein micelles: A diffusing wave spectroscopy and rheology approach

“…In this case, the maximum value of G 0 obtained for the highest concentration of kcarrageenan was 91 Pa. Lastly, for the HSM+agar, gelation occurred at an agar concentration of below 0.5% with the maximum G 0 value being 514 Pa at the agar concentration of 1.0%. For agar concentrations above 0.5%, the mixtures exhibited phase separation due to the thermodynamic incompatibility between the two components leading to the formation of a protein-rich and polysaccharide-rich phase (Bourriot, Garnier, & Doublier, 1999;Tolstoguzov, 2002). In general, it is important to note that we are not comparing HSM+k-carrageenan gels with HSM+agar gels, as the concentration range of polysaccharides probed in this work is different for both.…”

Structural aspects of legume proteins and nutraceutical properties

“…Interaction between legume and cereal proteins with carbohydrates has been the object of several investigations, aimed at the improvement in their technological properties and at the characterization of potential beneficial effects (Alzagtat & Alli, 2002;Tolstoguzov, 2002). Indeed, the role of starch-protein interaction in legumes and wheat in reducing the glycemic response and rate of glucose absorption was demonstrated by Jenkins et al (1987) and Thorne, Thompson, and Jenkins (1983).…”

Physical behaviour of dairy ingredients during ice cream processing

“…Thermodynamic incompatibility of biopolymers leads to phase separation resulting in localised concentrations of protein and stabilisers [22,27], which could alter the viscosity of the ice cream mix. Furthermore, the same phenomena is capable of contributing to the structure development and functionality of the hardened ice cream, by localizing high concentrations of milk protein at the ice crystal interface and exerting a water holding action, that markedly enhances the stabiliser effect [22].…”