Structure-Activity Relationships in Sweet Compounds

The sweetening strength of a compound can be measured numerically and expressed as  

a receptor for sweet compounds is to be depicted schematically as a hydrophobic pocket, containing a complementary nr/er system. 

It has been shown with numerous compounds that as the hydrophobicity and the space-filling properties of hydrophobic groups increase, the sweetening strength increases, passes through a maximum, and finally reaches a limit beyond which the sweet taste is either quenched or changes into a bitter taste. 

According to Nofre and TintU even the AH/B/X system does not adequately explain the effect of hyperpotent sweeteners, e. g., guanidine (cf. 8.8.12.2). They propose a sweetness receptor which should make the large differences in the structure and sweetening strength understandable. 

Saccharose in a 2.5 or 10% solution usually serves as the standard substance (/sac,g) Since the sweetening strength is concentration dependent (cf. Fig. 8.5), the concentration of the reference solution must always be given (/(cg)). When the sweetening strength of a substance is expressed as /sac,g(10) = 100, this means, e. g., that the substance is 100 times sweeter than a 10% saccharose solution or a 0.1% solution of this substance is isosweet with a 10% saccharose solution. 

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