Gastrophysics: Statistical thermodynamics of biomolecular denaturation and gelation from the Kirkwood-Buff theory towards the understanding of tofu

Sugars, alcohols, or salts, when added to food, affects the heat denaturation of proteins and the sol-gel transition of macromolecules. Such an effect of cosolvents has long been known and exploited; yet understanding how they work at a molecular level has been a matter of scientific debate for decades, because of the lack of a definitive theory which can provide a microscopic explanation. Here we show that a rigorous statistical thermodynamic theory, the Kirkwood-Buff (KB) theory, provides not only a long-awaited microscopic explanation but also a clear guideline on how to analyze experimental data. KB theory synthesizes the classical Wyman-Tanford formula and partial molar volume, and enables the determination of biomolecule-water and biomolecule-cosolvent interactions solely from experimental data. Nothing beyond the materials in introductory physical chemistry or chemical thermodynamics textbooks is necessary to follow the derivations presented in this review. (C) 2016 Elsevier Ltd. All rights reserved.