Title: Thermodynamics and non-equilibrium criteria
for development and application of supplemented phase diagrams
Chairman: Horacio R.
Austen Angell, Tony
Auffret, Harry Levine,
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:
The areas of food and pharmaceutical processing
in which theoretical basis are needed for a better definition of
the involved phenomena.
The practical/theoretical applicability of equations
extensively employed to predict transition temperatures.
Which is the best standard procedure to determine
the glass transition curve over the water content scale.
Differences between methods based on thermodynamics
and kinetics to determine the phase/state transitions, and how could
they be standardized.
What is the effect of water content on the kinetics
of phase/state transitions (glass temperature, crystallization temperature)
How can be state diagrams applied to analyze the
stability of biomolecules under extreme conditions (i.e. frozen
systems, high or low pressures).
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.
to database (in progress)
Last update: 19 March 2007
<project announcement published