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Pure Appl. Chem., 2010, Vol. 82, No. 5, pp. 1065-1097

Published online 2010-04-20

Empirical and theoretical models of equilibrium and non-equilibrium transition temperatures of supplemented phase diagrams in aqueous systems (IUPAC Technical Report)

Horacio R. Corti1*, C. Austen Angell2, Tony Auffret3, Harry Levine4, M. Pilar Buera1, David S. Reid5, Yrjö H. Roos6 and Louise Slade4

1 Faculty of Exact and Natural Sciences, University of Buenos Aires, Int. Cantilo s/n. Pabellón II Ciudad Universitaria, Buenos Aires, Argentina
2 Department of Chemistry, Arizona State University, Tempe, AZ 85287, USA
3 Global Research & Development, Pfizer, Ltd., Ramsgate Road, Sandwich, Kent CT13 9NJ, UK
4 Food Polymer Science Consultancy, Morris Plains, NJ 07950, USA
5 Department of Food Science and Technology, University of California at Davis, 1 Shields Ave., Davis, CA 95616-8571, USA
6 Department of Food and Nutritional Sciences, University College, Cork, Ireland

Abstract: This paper describes the main thermodynamic concepts related to the construction of supplemented phase (or state) diagrams (SPDs) for aqueous solutions containing vitrifying agents used in the cryo- and dehydro-preservation of natural (foods, seeds, etc.) and synthetic (pharmaceuticals) products. It also reviews the empirical and theoretical equations employed to predict equilibrium transitions (ice freezing, solute solubility) and non-equilibrium transitions (glass transition and the extrapolated freezing curve). The comparison with experimental results is restricted to carbohydrate aqueous solutions, because these are the most widely used cryoprotectant agents. The paper identifies the best standard procedure to determine the glass transition curve over the entire water-content scale, and how to determine the temperature and concentration of the maximally freeze-concentrated solution.