UMAMI PEPTIDES - ASSESSMENT OF THEIR ALLEGED TASTE PROPERTIES

In the literature there are reports that 31 di- and tripeptides elicit umami (i.e. monosodium L-glutamate-like or MSG-like) or savoury taste s. However, the occurrence of ''umami peptides'' is questioned with re gard to the high specificity of those that give an umami taste. A tota l of 12 dipeptides and 4 tripeptides were selected for a re-examinatio n of their taste properties. Criteria were that: (1) their taste has b een described as umami, savoury or brothy; (2) they have a threshold v alue; and (3) they should fit into the theoretical framework of L-glut amyl peptides discussed. The peptides - in aqueous solutions, at room temperature, at pH 6.0 and 4.0, and at concentrations well above the r eported threshold values - were tasted. Panel members were selected on the basis of their ability to perceive the umami taste of 2.67 mM MSG at pH 6.0. None of the peptides tested was found to elicit an umami t aste. The taste of L-glutamic acid in the peptides was lost and furthe rmore the taste of bitter amino acids in the peptides was no longer pe rceivable. Within the range of Glu-X peptides, even Glu-Glu and Glu-As p, which have previously been reported to elicit umami tastes, did not taste MSG-like either in pure solution or in the presence of sodium c hloride. The tripeptide Ala-Glu-Ala, reported to have an ''umami thres hold'' value as low as 0.8 mM, was found not to have an umami taste or any other specific taste up to 10 mM. The general occurrence of umami peptides appears to be highly unlikely.