Sweet sugar, temperature dependence

Fig. 4.4. Temperature dependence of the relative sweetness of some sugars (based on saccharose = 100 at each...

Fructose is unique among known sugars in being sweeter than sucrose. In solution, fructose can exist as four or five isomers, and the relative sweetness of a solution is dependent upon the equilibrium between the sweeter pyranose isomers and the less sweet furanose isomers, which is in turn dependent on such conditions as pH and temperature. In cold conditions the pyranose form predominates and, therefore, fructose solutions are sweeter (Danisco Sweeteners, 2003). Fructose has a clean, sweet taste it is also synergistic with many bulk and intense sweeteners and is often used at low levels to improve the taste profile of some intense sweeteners. It is very soluble and also relatively hygroscopic, compared with sucrose (Danisco Sweeteners, 2003). 

Sucrose has a particularly full taste, which is acceptable even at high concentrations. It is therefore used as a standard for sweet taste in the sensory evaluation of sweet substances. The threshold values of some sugars in aqueous solutions are listed in Table 8.37. For practical reasons, the sweetness of substances is expressed as a multiple of the sweetness of the sucrose solution (mainly 10% solution). The relative sweetness of certain sugars and sugar alcohols is given in Table 8.38. These values are only approximate, as they depend on sugar concentration, type and amount of anomers, temperature, presence of other substances and other factors. 

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