Synthesis and Sensory Characterization of Novel Umami-Tasting Glutamate Glycoconjugates
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- 作者：Ersan Beksan ; Peter Schieberle ; Fabien Robert ; Imre Blank ; Laurent Bernard Fay ; Hedwig Schlichtherle-Cerny ; and Thomas Hofmann
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2003
- 出版时间：August 27, 2003
- 年：2003
- 卷：51
- 期：18
- 页码：5428 - 5436
- 全文大小：174K
- 年卷期：v.51,no.18(August 27, 2003)
- ISSN：1520-5118
文摘
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-mimeticapproaches, and their chemical structures have unequivocally been elucidated by 1D- and 2D-NMRand MS experiments. Systematic sensory studies revealed that both glycoconjugates exhibitpronounced umami-like taste with recognition taste thresholds of 1-2 mmol/L, close to that ofmonosodium glutamate (MSG). Contrary to an aqueous solution of MSG, 1 does not show the sweetishand slightly soapy by-note, but evokes an intense umami taste. Aqueous solutions of 2 were describedby the descriptors umami, seasoning, and bouillon-like. Added to a bouillon base, which did not containany taste enhancers, both glycoconjugates imparted a distinct umami character similar to the controlsample containing the same amount of MSG on a molar basis. To the best of our knowledge, thesetypes of glycoconjugates in general and, in particular, N-glucosyl glutamate and N-deoxyfructosylglutamate 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 similarto the umami reference compound MSG. Systematic 13C NMR measurements revealed that 1 wasfairly 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 ofhuman saliva.Keywords: Umami; taste; N-glucoside; Maillard reaction; Amadori product; glutamate; MSG; N-(D-glucos-1-yl)-L-glutamate; N-(1-deoxy-D-fructos-1-yl)-L-glutamic acid; saliva