Glass transition prediction strategies based on the Couchman-Karasz equation in model confectionary systems

Emily J. Mayhew, Cheyenne H. Neal, Soo Yeun Lee, Shelly J. Schmidt

Research output: Contribution to journalArticle


Our objectives were to compare the Couchman-Karasz-predicted glass transition temperature, TCK, to the measured glass transition temperature of a mixture, Tgm, of model confectionary systems and develop an empirical correction to improve the accuracy of prediction. Results showed that the original Couchman-Karasz equation fit the data better than the modified equation; although both generally overestimated Tgm. Blends containing sorbitol had the largest ΔTgmCK, where ΔTgmCK=TCK−Tgm. While Tgm varied with composition, the increase in Tgm with decreasing moisture content was linear (R2¯=0.984. and consistent across blends (4.5 ± 0.9°C/1% moisture, wb). The increase in Tgm with increasing cook temperature was best described by a polynomial model (R2¯=0.998), but adequately described by a more generalizable linear model (R2¯=0.979). Application of an empirical correction based on moisture content or cook temperature and TCK of dry ingredients reduced the average ΔTgmCK from 20.1 °C and 11.3 °C for modified and original equations, respectively, to <5.6 °C.

Original languageEnglish (US)
Pages (from-to)287-302
Number of pages16
JournalJournal of Food Engineering
StatePublished - Dec 2017



  • Carbohydrates
  • Confections
  • Couchman-Karasz equation
  • Glass transition
  • Polyols
  • Sugar replacement

ASJC Scopus subject areas

  • Food Science

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