Dynamic Isopiestic Method (DIM): Measuring Moisture Sorption Isotherm of Freeze-Dried Garlic Powder and Other Potential Uses of DIM

Abstract

Moisture sorption (adsorption and desorption) isotherm of freeze-dried garlic powder was measured by static and dynamic isopiestic methods. Isotherms measured by static isopiestic method produced deviations from the dynamic method at the lower and higher water activity ranges. Dynamic method showed that the temperature had more effects on desorption isotherms compared to the adsorption isotherm, and the degree of isotherm hysteresis reduced with the increase of equilibration temperature. The isotherm was fitted with BET, GAB, and Norrish models. Critical evaluations on the physical meaning of the model parameters are presented. The dynamic method has the potential to be used in studying other structural and drying characteristics of foods.

Keywords:

• Moisture isotherm
• Isopiestic method
• Garlic
• Dynamic vapor sorption (DVS)
• Autosorp

ACKNOWLEDGMENTS

This work was supported by the Sultan Qaboos University research grants IG/AGR/BIOR/05/01. The author would like to thank Dr. Bhesh Bhandari for his valuable comments on the manuscript.

Notes

41. Comino, P.R. The Sorption Isotherm Properties of Limonene-β-cyclodextrin complex powder. Master of Philosophy Thesis, The University of Queensland, 2005.