Investigation of the heating rate dependency associated with the loss of crystalline structure in sucrose, glucose, and fructose using a thermal analysis approach (Part I)

Joo Won Lee, Leonard C. Thomas, Shelly J. Schmidt

Research output: Contribution to journalArticlepeer-review

Abstract

Thermodynamic melting occurs at a single, time-independent temperature with a constant enthalpy value. However, substantial variation in the melting parameters (Tm onset, Tm peak, and ΔH) for sucrose, glucose, and fructose has been reported in the literature. Although a number of explanations have been put forth, they do not completely account for the observed variation. Thus, this research was performed to elucidate the fundamental mechanism underlying the loss of crystalline structure in the sugars using both thermal (Part I) and chemical (Part II) analysis approaches. A strong heating rate dependency observed in the melting parameters for the sugars implies the occurrence of a kinetic process during the loss of crystalline structure. The difference in heat capacity and modulated heat flow amplitude in the stepwise quasi-isothermal modulated differential scanning calorimetry experiments for the sugars compared to indium and mannitol (thermodynamic melting comparison materials) strongly suggests thermal decomposition as the kinetic process responsible for the loss of crystalline structure, which is the critical difference between our conclusion and others. We propose the term "apparent melting" to distinguish the loss of crystalline structure due to a kinetic process, such as thermal decomposition, from thermodynamic melting.

Original languageEnglish (US)
Pages (from-to)684-701
Number of pages18
JournalJournal of Agricultural and Food Chemistry
Volume59
Issue number2
DOIs
StatePublished - Jan 26 2011

Keywords

  • (modulated) differential scanning calorimetry
  • Thermodynamic melting
  • apparent melting
  • fructose
  • glucose
  • kinetic processes
  • sucrose
  • thermal decomposition
  • thermogravimetric analysis

ASJC Scopus subject areas

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)

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