Abstract: 2-(4-Methoxyphenoxy) propionic acid (HPMP) is a widely used sweetness inhibitor, but its structure-activity relationship remains unclear. The purpose of this study is to investigate the effect of the hydrophobic group at the para-position of HPMP on its sweetness inhibitory activity aiming at providing a theoretical basis for the exploration of novel sweetness inhibitors to improve the eating quality of high-energy, sports and traditional high-sugar foods. In this study, HPMP and four derivatives were synthesized. An electronic tongue method was established to evaluate the inhibitory effect of HPMP and its derivatives on the sweetness of sucrose, fructose, xylitol and sorbitol. The results showed that the electronic tongue could reflect the sweetness inhibition of HPMP and there was a good correlation between the results of electronic tongue and sensory evaluation. Therefore, the electronic tongue could be applied to evaluate sweetness inhibition. It was found that HPMP and its derivatives all inhibited the sweetness of the four sweeteners. When the para-carbon of the aromatic ring borne different alkoxy groups, sweetness inhibition rates decreased with increasing volume of substituents. The derivatives modified with smaller hydrophobic groups such as methyl and chlorine atoms had a similar sweetness inhibitory potency to HPMP. It can be assumed that the spatial volume of hydrophobic substituents at the para-position is a significant factor affecting the sweetness inhibitory effect.

Key words: 2-(4-methoxyphenoxy) propionic acid; sweetness inhibition; structure-activity relationship; derivative; electronic tongue