Measurement of Water Activity Coefficient in Saccharide-Water 
Systems by Freezing Point Depression 

Tomoharu OKUDA, Tohru SHIBATA, 
Takaharu KAMEOKA and Masaru MlZOGUCHI

Faculty of Bioresources, Mie University 

Abstract 

Interactions between water and saccharide in food are very 
important. The water activity coefficient in saccharide-water
systems was measured by freezing point depression. Glucose-water
 systems were used, being ideal solutions. Freezing point depression
 in these systems was proportional to mole fraction and the 
accuracy of the experimental data was confirmed. Maltose-water 
systems behaved as ideal solutions. For two systems, water activity 
coefficient decreased from l.Oat mole fractions above 0.02 in 
sucrose-water systems. 

Key words: 
saccharide, water activity , water activity, glucose , maltose, 
sucrose, freezing point depression coefficient