33-2 |
Use of isothermal microcalorimetry to determine kinetic and thermodynamic parameters from complex, heterogeneous biological systems for the prediction of shelf life |
M. A. A. O'NEILL and A. E. Beezer. Natural Resources Institute, Univ. of Greenwich, Medway, Central Ave., Chatham Maritime, Kent, ME4 4TB, United Kingdom The use of isothermal micro-calorimetry for the determination of kinetic and thermodynamic information for a wide variety of systems is well known. Recent advances now allow the kinetic information to be derived directly from the calorimetric data, for homogeneous and heterogeneous systems, free from any assumption. Calorimetry therefore is now a powerful tool for the determination of accurate values for rate constants, k, (and of course enthalpy of reaction). Knowledge of k is vital for the determination of stability and hence shelf life. This presentation will outline some of the theoretical issues involved in the determination of thermo-kinetic information from complex systems and will show how these ideas have been applied to the study of a number of complex, heterogeneous biological systems. One such study was performed on freshly squeezed orange juice. It is seen that the component reactions, contributing to the overall calorimetric signal, can be isolated and characterized in terms of their thermodynamic and kinetic parameters. Knowledge of these parameters also allows identification and quantitative analysis of the reagents responsible for the calorimetric signal, namely pectin and ascorbic acid. Another example of the application of calorimetry to the study of biological systems is the study of osmotic drying of fruit; this is exemplified through a study on apple segments the results of which are briefly discussed
Session 33, Applications of calorimetry in food and biological materials
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