Synthesis and Sensory Characterization of Novel Umami-Tasting Glutamate Glycoconjugates

Abstract

Two glycoconjugates of glutamic acid, namely, the N-glycoside dipotassium N-(d-glucos-1-yl)-l-glutamate (1) and the corresponding Amadori compound N-(1-deoxy-d-fructos-1-yl)-l-glutamic acid (2), have been synthesized in yields of 35 and 52%, respectively, using new Maillard-mimetic approaches, and their chemical structures have unequivocally been elucidated by 1D- and 2D-NMR and MS experiments. Systematic sensory studies revealed that both glycoconjugates exhibit pronounced umami-like taste with recognition taste thresholds of 1-2 mmol/L, close to that of monosodium glutamate (MSG). Contrary to an aqueous solution of MSG, 1 does not show the sweetish and slightly soapy by-note, but evokes an intense umami taste. Aqueous solutions of 2 were described by the descriptors umami, seasoning, and bouillon-like. Added to a bouillon base, which did not contain any taste enhancers, both glycoconjugates imparted a distinct umami character similar to the control sample containing the same amount of MSG on a molar basis. To the best of our knowledge, these types of glycoconjugates in general and, in particular, N-glucosyl glutamate and N-deoxyfructosyl glutamate have never been reported as taste active compounds having umami-like properties. Therefore, 1 and 2 represent a new class of umami-type taste compounds showing properties similar to the umami reference compound MSG. Systematic (13)C NMR measurements revealed that 1 was fairly stable in aqueous solutions under alkaline conditions (pH 8-10) as well as in dry form. However, it rapidly hydrolyzes in neutral and acidic solutions, giving rise to glucose and glutamate. In contrast, glycoconjugate 2 was observed to be rather stable in aqueous solution as well as in the presence of human saliva.

Interaction Between Umami Peptide and Taste Receptor T1R1/T1R3

“…One should be careful with the selection of the appropriate fragment of a protein for such a modeling. As both the presence and the absence of a single amino acid could, in principle, result in One can therefore conclude that docking is a reliable technique for finding the binding site of rigid ligands up to at least 30 heavy atoms [23].…”

Basic Chemistry and Process Conditions for Reaction Flavours with Particular Focus on Maillard‐Type Reactions

“…As an example, Alapyridaine has been identified in Maillard model systems containing hexose sugars and alanine as well as in beef broth as an essential compound enhancing the sweet taste and umami character in beef broth (Ottinger and Hofmann, 2003;Soldo et al, 2003). Glycoconjugates of glutamic acid, namely the N-glycoside dipotassium N-(d-glucos-1-yl)-l-glutamate and the corresponding Amadori compound N-(1-deoxy-d-fructos-1-yl)-l-glutamic acid (Fru-Glu), were found by systematic sensory studies to exhibit a pronounced umami-like taste, with recognition taste thresholds of 1-2 mmol/L, close to that of monosodium glutamate (MSG) (Beksan et al, 2003). Contrary to MSG, they do not show the sweetish and slightly soapy by-note, but evoke an intense umami, seasoning, and bouillon-like taste.…”

Systematic studies of structure and physiological activity of alapyridaine. A novel food‐born taste enhancer

“…1 H, 13 C, and DEPT-135 NMR experiments were performed on Bruker AC-250 and AV-360 spectrometers. 1 H, COSY, HMQC, and HMBC measurements were performed on a Bruker AMX 400-III spectrometer (Bruker, Rheinstetten, Germany).…”

“…In addition, lactic acid was found to contribute to the glutamate-like taste of foods such as beef bouillon and stewed beef juice [7,8]. Moreover, hydrophilic di-, tri-, and tetrapeptides containing polar side chains, such as Glu-Asp, Glu-Glu, Asp-Glu-Ser, and Asp-Asp-Asp-Asp [9 -11], N-lactoyl-L-glutamate, the condensation product of lactic acid and glutamic acid [12], as well as the glutamate glycoconjugates N-(D-glucos-1-yl)-L-glutamate and N-(1-deoxy-D-fructos-1-yl)-L-gluta-mate [13], were reported to evoke bouillon-like umami taste and to have a long-lasting and mouth-watering sensation in combination with flavor-enhancing characteristics.…”