Mechanism of the perception of “kokumi” substances and the sensory characteristics of the “kokumi” peptide, γ-Glu-Val-Gly

Abstract

Some foods are known to have flavours that cannot be explained by the five basic tastes alone, such as continuity, mouthfulness and thick flavour. It was demonstrated that these sensations are evoked by the addition of kokumi substances, flavour modifiers that have no taste themselves. However, their mode of action has been poorly understood. During a study on the perception of amino acids and peptides, it was found that glutathione (GSH) was one of the agonists of the calcium-sensing receptor (CaSR). We have hypothesized that CaSR is involved in the perception of kokumi substances. We found that all CaSR agonists tested act as kokumi substances and that a positive correlation exists between the CaSR activity of γ-glutamyl peptides and kokumi intensity. Furthermore, the kokumi intensities of GSH and γ-Glu-Val-Gly, a potent kokumi peptide, were significantly reduced by the CaSR-specific antagonist, NPS-2143. These results suggest that CaSR is involved in the perception of kokumi substances. A potent kokumi peptide, γ-Glu-Val-Gly, enhanced sweetness, saltiness and umami when added to 3.3% sucrose, 0.9% NaCl and 0.5% MSG solutions, respectively. In addition, γ-Glu-Val-Gly enhanced the intensity of continuity, mouthfulness and thick flavour when added to chicken soup and reduced-fat cream. These results suggest that γ-Glu-Val-Gly is a potent kokumi peptide and would be useful for improving the flavour of food.