  2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center  |
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Phase transitions in starch: Applications to the processing of cereal products. John Mitchell. Division of Food Sciences, School of Biosciences, University of Nottingham Loughborough LE12 5RD United Kingdom.
Ideas originally developed for synthetic polymers have been extensively applied to starch. Central to this approach is the determination of two temperatures; Tm (the melting temperature) and Tg (the glass transition temperature). Examples of the determination of these temperatures by rheological and other methods will be given At low water contents Tm and Tg are strongly dependent on the water and sugar content of the system and this dependence can be used to model the rate of retrogradation of cereal products and to predict the degree of starch conversion during conventional and extrusion processing of cereal systems. More recently these concepts have been extended to embrace the influence of partition of water between different components in mixed systems and events occurring below the glass transition temperature, in particular the physical ageing of starch systems. It is emphasised that although these ideas are of great value in providing a framework that can guide thinking, food systems are complicated and a polymer science approach should not be applied uncritically.
Copyright 2001
The American Association of Cereal Chemists