Pure isomalt has a low solubility (28% at 25°C). This solubility increases with increasing temperature.
Note, however, that the isomalt syrup produced by Cargill (C*IsoMaltidex™ LQ 16510 Isomalt) exhibits similar properties as isomalt powder, but does not require the dissolution step during the manufacturing of confectionery products.
[IMAGE:isomaltidex solubility graph]
Solubility of isomalt in water at different temperatures compared to other polyols and sucrose
Isomalt crystals are non-hygroscopic as shown on this image.
This ability to not absorb water is a significant property for hard candies and coating, where isomalt is mostly used. This stability against moisture pick-up contributes to an extended shelf life of the products. Isomalt is, therefore, recommended for hard candies that must resist extreme storage conditions (hot and humid climates) and/or do not require individual wrapping (unwrapped candies in pocket size boxes). Isomalt-based hard candies show a better storage stability than other traditional hard-boiled sweets.
[IMAGE:sorption isotherms of polyols]
Sorption isotherms of polyols
Melting point and glass transition temperature
Isomalt crystals melt at a temperature between 145 and 150°C.
The glass transition temperature (Tg) of isomalt is above room temperature. This means that, at room temperature, isomalt is in a glassy state and will not crystallize (since crystallization can only occur at temperature above Tg). This property allows the production of clear hard candies.
[IMAGE:Isomalt melting point]
Melting point of isomalt compared to other polyols and sugars
Isomalt is a combination of two components. The ratio of these two components has a significant influence on the micro-crystallization speed of isomalt-based confectionery products.
Cargill's pure crystalline isomalt contains the correct balance of these two substances to guarantee a slow micro-crystallization on the candy surface, while keeping the advantages of low hygroscopicity and non-stickiness.
Heat of solution
When isomalt is dissolved in water, the crystals need very little energy to dissolve. Isomalt is, therefore, characterized by a low negative heat of solution (- 9.4 cal/g) as shown in the chart below. This means that, unlike other polyols, isomalt exhibits no cooling effect similar to sucrose.
[IMAGE:cooling effect of isomalt]
Heat of solution / cooling effect of isomalt
Isomalt's chemical properties are similar to those of other polyols in that it has no reducing end-groups and thus has excellent heat and acid stability.
pH: Isomalt resists decomposition both in acidic or alkaline media and remains stable under prolonged exposure to pHs in the range of 2 to 10.
Temperature: The excellent heat stability of isomalt ensures no product decomposition and/or discoloration at temperatures up to 160°.
Storage: Isomalt has an excellent stability upon storage.
Isomalt is a bulk sweetener exhibiting a very clean sucrose-like taste profile with no significant off-tastes or aftertastes. Also like sucrose, its bulk properties translate into a significant body and smooth mouthfeel, as displayed in the chart below.
[IMAGE:profile of isomalt and sucrose in water]
Profile of isomalt and sucrose in water at 7% sucrose equivalent value (SEV)
Unlike other polyols, isomalt exhibits no cooling effect like sucrose. Cargill's isomalt liquid grade contains a blend of pure crystalline isomalt and maltitol syrup. The presence of maltitol syrup in the end product is in many candy recipes referred to as improving the flavor release.
[IMAGE:cooling effect vs polyols]
Cooling effect of isomalt compared to other polyols and sucrose -50g sample in 100g water
Isomalt has a sweetness potency that is 50% that of sucrose. Consequently, when using pure crystalline isomalt, a combination with an intense sweetener may be required.
When using Cargill's liquid isomalt grade (C*IsoMaltidex LQ 16510), the sweetness is increased due to the presence of maltitol syrup. Thus, isomalt achieves a satisfactory sweetness level in end products.
The sweetness temporal profile of a compound is a measure of its sweetness intensity over time. It is an important property used to differentiate sweeteners.
Unlike most intense sweeteners, the sweetness temporal profile of isomalt and of polyols in general is similar to the one of sucrose. Isomalt provides a quick sweetness perception and a short sweet linger.