Taste-active glycoconjugates of glutamate: New umami compounds

Hydrolyzed plant proteins are widely used as ingredients in culinary products for their glutamate-like "umami" taste. The comparison of the taste profiles of three different wheat gluten hydrolysates revealed that the enzymatic hydrolysate of acid-deamidated wheat gluten elicited an intense glutamate-like taste. The hydrolysate was analyzed by "LC-tasting", a technique comprising stepwise fractionation of a food by different chromatographic methods, such as gel permeation chromatography and RP-HPLC, followed by the sensory evaluation of the obtained fractions after lyophilization. The chemical analysis of the most intense glutamate-like subfraction by hydrophilic interaction liquid chromatography coupled to electrospray ionization mass spectrometry (HILIC-ESI-MS) revealed many hydrophilic glutamyl di- and tripeptides, as well as the presence of different glycoconjugates of glutamate, glutamine, and lysine. The most abundant Amadori compound, N-(1-deoxy-fructos-1-yl) glutamate, was identified as eliciting an intense umami taste. The glycoconjugates of glutamate were identified as a new class of compounds imparting umami taste to foods.