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Current Project

Physical and Biophysical Chemistry Division (I)


Number: 2003-036-2-100

Title: Thermodynamics and non-equilibrium criteria for development and application of supplemented phase diagrams

Task Group
: Horacio R. Corti

Members: C. Austen Angell, Tony Auffret, Harry Levine, María del Pilar Buera, David S. Reid, Yrjo Roos, and Louise Slade

The aim of the project is to establish rational links between thermodynamic aspects of phase diagrams supplemented by the non equilibrium curve of the glass transition temperature for mixtures of water with vitrifying agents used in the cryo and dehydropreservation of natural (foods, seeds, etc.) and synthetic products (pharmaceuticals). It will contribute to improve processing and conservation practices of these important materials.It intends not just to compile information that already exists, but to consider all the sort of basic and applied problems that one should consider when managing these phase/state diagrams.

The present proposal is prepared as to have a very broad and interdisciplinary scope for impacting on many fields related to chemistry and biophysical chemistry. It would permit promoting IUPAC activities and competence to a wider non-chemistry scientific community. It is largely inspired in early activities of the International Symposia on the Properties of Water (ISOPOW). The applicability of state diagrams is recognized in food chemistry and related areas. However, many basic questions are still open and more precise definitions are needed for a correct interpretation of the involved phenomena.The practical aim of the project is to give solid basis to develop supplemented state diagrams of aqueous glassy formers, such as saccharides, polyols, etc., in order to describe the influence of water content, nature of the vitrifying agent and temperature on the physico-chemical stability of natural and synthetic products.

To fulfill this goal this study proposes to analyze:

  1. The areas of food and pharmaceutical processing in which theoretical basis are needed for a better definition of the involved phenomena.
  2. The practical/theoretical applicability of equations extensively employed to predict transition temperatures.
  3. Which is the best standard procedure to determine the glass transition curve over the water content scale.
  4. Differences between methods based on thermodynamics and kinetics to determine the phase/state transitions, and how could they be standardized.
  5. What is the effect of water content on the kinetics of phase/state transitions (glass temperature, crystallization temperature) in biomaterials.
  6. How can be state diagrams applied to analyze the stability of biomolecules under extreme conditions (i.e. frozen systems, high or low pressures).
  7. How can multidimentional (ternary systems, pressure coordinate) diagrams be managed. The project will aim to give scientific-based definitions in the detected critical areas.

June 2005 - The update and literature classification on supplemental phase diagrams for relevant aqueous systems for food and pharmaceuticals has been completed. The initial critical evaluation of this database includes the shortcomings of current practice.

> link to database (in progress)

Last update: 19 March 2007

<project announcement published in Chem. Int. Sep-Oct 2004>


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Page last modified 19 September 2007.
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