Measuring the deliquescence point of crystalline sucrose as a function of temperature using a new automatic isotherm generator

Wei Yao, Xin Yu, Joo Won Lee, Xiaoda Yuan, Shelly J. Schmidt

Research output: Contribution to journalArticlepeer-review


The relative humidity at which crystalline materials begin adsorbing large quantities of water from the atmosphere, termed the deliquescence point (RH o), is an important temperature dependent stability parameter. The RHo of a number of food and pharmaceutical materials has been determined at 25°C, but it is difficult to find RHo values in the literature at other temperatures, even for common food materials, such as sucrose. Thus, the primary objective of this research was to assess the effect of temperature on RHo for crystalline sucrose using a new automatic isotherm generator. A secondary objective was to determine and compare the RHo value using three other methods (RH after the MC step change method, and two smoothing and second derivative methods [Savitzky-Golay and Yuan and others]), in addition to the commonly used linear extrapolation method. The AquaSorp DDI method provides an accurate, fast, and convenient means of measuring the initial real-time aw values of the adsorption of water by the crystalline solid, making the DDI method an outstanding RHo measuring method. A decrease in RHo with increasing temperature was observed and attributed to increasing sucrose solubility with increasing temperature. No statistical difference (p = 0.05) was found between the four RHo determination methods at each temperature, with the linear extrapolation method yielding RHo values of 85.9, 85.7, and 84.0% at 15, 25, and 35°C, respectively.

Original languageEnglish (US)
Pages (from-to)882-893
Number of pages12
JournalInternational Journal of Food Properties
Issue number4
StatePublished - Jul 2011


  • AquaSorp isotherm generator
  • Deliquescence
  • Relative humidity
  • Sucrose
  • Water activity

ASJC Scopus subject areas

  • Food Science


Dive into the research topics of 'Measuring the deliquescence point of crystalline sucrose as a function of temperature using a new automatic isotherm generator'. Together they form a unique fingerprint.

Cite this