Investigating the moisture sorption behavior of amorphous sucrose using a dynamic humidity generating instrument

X. Yu, S. M. Kappes, L. A. Bello-Perez, S. J. Schmidt

Research output: Contribution to journalArticlepeer-review

Abstract

The moisture sorption behavior of freeze-dried amorphous sucrose was investigated using a dynamic humidity generating instrument, the Dynamic Vapor Sorption (DVS) instrument. The kinetic moisture sorption profiles of freeze-dried amorphous sucrose samples with 29% crystalline content were obtained using the DVS instrument at 9 relative humidity (RH) values, ranging from 10% to 90%, at 25°C. Moisture-induced crystallization was observed for %RH values between 40% and 80%, where the crystallization onset time decreased as %RH increased. The moisture sorption behavior of freeze-dried amorphous sucrose with 3 crystalline contents, 23%, 29%, and 80%, was also compared, revealing that the crystalline content had a significant impact on the pseudo-sorption isotherm of freeze-dried amorphous sucrose. In general, for %RH values below 90%, samples that had a lower percent crystalline content had a higher pseudo-equilibrium moisture content, with the difference becoming most pronounced for the 60% to 80% RH values. The moisture-induced crystallization results as a function of %RH obtained in this study were compared to those previously reported in the literature, leading to an extensive discussion of both the experimental protocols used and the hypothesized mechanisms governing the long-term stability of amorphous materials. The hypothesized mechanisms discussed included the glass transition temperature boundary, the zero mobility temperature, and the hydration limit. Based on the dissimilarity in these hypothesized mechanisms, additional theoretical and experimental exploration is still merited in order to adequately predict the conditions (for example, moisture content, %RH, and temperature) required to ensure long-term stability of amorphous solids.

Original languageEnglish (US)
Pages (from-to)E25-E35
JournalJournal of food science
Volume73
Issue number1
DOIs
StatePublished - Jan 1 2008

Keywords

  • Amorphous sucrose
  • Crystallization onset time
  • Dynamic vapor sorption
  • Moisture-induced crystallization
  • Pseudo-moisture sorption isotherms
  • Stability

ASJC Scopus subject areas

  • Food Science

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