Differential sweetness of commercial sour liquids elicited by miracle fruit in healthy young adults

Abstract

Miracle fruit (Synsepalum dulcificum) contains the glycoprotein miraculin which turns a sour taste into a sweet one. Chemical analyses and sensory evaluation experiments were conducted to examine the sweetening effect of miracle fruit with regard to five different commercial sour liquids which were diluted until they were subjectively equally sour. HPLC-based analyses revealed that (1) the predominating acids in two and three of the liquids were citric acid and acetic acid, respectively and (2) all five liquids contained fructose and glucose. Healthy young adults (eight males and 10 females) in the sensory evaluation experiments were asked to chew a miracle fruit and apply their saliva to the oral mucosae. They were asked to score the sweetness elicited by the five liquids relative to a sucrose standard at 0, 15, 25 and 35 min thereafter. The citric acid-based liquids were perceived as being sweeter than the acetic acid-based liquids at all timepoints. Thus, commercial sour liquids that mainly contain citric acid are more effective than acetic acid-based liquids in eliciting a perception of sweetness after the miracle fruit application, while the sugars in the liquids seemed to play a minimal role as determinants of sweetness.