Article

Can the Thermodynamic Melting Temperature of Sucrose, Glucose, and Fructose Be Measured Using Rapid-Scanning Differential Scanning Calorimetry (DSC)?

Department of Food Science and Human Nutrition, University of Illinois at Urbana−Champaign, 399A Bevier Hall, 905 South Goodwin Avenue, Urbana, Illinois 61801, United States
DSC Solutions LLC, 27 East Braeburn Drive, Smyrna, Delaware 19977, United States
Department of Food Science and Human Nutrition, 367 Bevier Hall, University of Illinois at Urbana−Champaign, 905 South Goodwin Avenue, Urbana, Illinois 61801, United States
J. Agric. Food Chem., 2011, 59 (7), pp 3306–3310
DOI: 10.1021/jf104852u
Publication Date (Web): March 18, 2011
Copyright © 2011 American Chemical Society
*Phone: (217) 333-6963. Fax: (217) 265-0925. E-mail: sjs@illinois.edu.

Abstract

The loss of crystalline structure in sucrose, glucose, and fructose has been shown to be due to the kinetic process of thermal decomposition (termed apparent melting), rather than thermodynamic melting. The purpose of this research was to investigate whether or not it is possible to scan quickly enough to suppress the kinetic process of thermal decomposition and reach the thermodynamic melting temperature of these sugars using a new rapid-scanning DSC. Indium, a thermodynamic melting material, and sucrose, glucose, and fructose were analyzed at three heating rates from 1 to 25 °C/min using standard DSC and at seven heating rates from 50 to 2000 °C/min using rapid-scanning DSC. Thermodynamic melting was achieved when the onset temperature (Tm onset) of the endothermic peak leveled off to a constant value independent of heating rate. The Tm onset for indium was constant (156.74 ± 0.42 °C) at all heating rates. In the case of fructose, the Tm onset increased considerably until a heating rate of approximately 698 °C/min, after which the average Tm onset for the remaining three heating rates was constant at 135.83 ± 1.14 °C. Thus, 135.83 °C is proposed to be the thermodynamic melting temperature of fructose. It is important to note that the heating rate at which this thermodynamic melting temperature is achieved is most likely influenced by the type and amount of trace components (e.g., water and salts) contained in the fructose, which are known to vary widely in sugars. In the case of sucrose and glucose, thermodynamic melting temperatures were not able to be obtained, because the upper limit heating rate used was not fast enough to suppress thermal decomposition and achieve thermodynamic melting, perhaps due to the higher apparent Tm onset for sucrose and glucose compared to that for fructose.

Supporting Information


Material information for sucrose, glucose, and fructose obtained from the Sigma-Aldrich Co. and analyzed by the authors of this study. This material is available free of charge via the Internet at http://pubs.acs.org.

Citation data is made available by participants in CrossRef's Cited-by Linking service. For a more comprehensive list of citations to this article, users are encouraged to perform a search in SciFinder.

Metrics

Received 16 December 2010
Date accepted 7 March 2011
Published online 18 March 2011
Published in print 13 April 2011
Explore by: