Title: Alternative Sweeteners

Isomalt 269
IV. PHYSICO-CHEMICAL PROPERTIES
A. Physical Properties
The sorption isotherm (see Fig. 4) shows that isomalt has a very low water activity.
At 25°C isomalt absorbs virtually no water up to a relative humidity of 85%.
Furthermore, isomalt does not start absorbing water until the temperature reaches
60°C at 75% relative humidity (rh) or 80°C at 65% rh (9). This very low hygroscopicity
means that isomalt can be stored easily and distributed without much
special care. Furthermore, this explains why products exclusively or mainly based
on isomalt (e.g., hard candies) tend to be not sticky and have a long shelf-life.
As depicted in Fig. 5, the solubility of isomalt-ST is much lower than
that of sugar at 20°C, namely 24.5 g/100 g solution compared with a value of
66.7 g/100 g solution for sugar (4, 9). Because of its low solubility, oversaturated
solutions can be obtained with a relatively low concentration of isomalt. The
solubility of isomalt increases with increasing temperature and is comparable to
sucrose at most processing temperatures (85°C).
Figure 4 Sorption isotherm for isomalt-ST at three temperatures (25, 60, and 80°C);
w s is the amount of water absorbed by isomalt (kg water/kg isomalt).