Molecular and Sensory Studies on the Umami Taste of Japanese Green Tea

摘要

Aimed at defining the key drivers for the quality-determining umami taste of a high-grade powdered green tea,called mat-cha,a bioactivity-guided fractionation using solvent extraction,solvent precipitation,preparative chromatographic separations,and human psychophysical experiments was applied on freshly prepared mat-cha.Liquid chromatography-tandem mass spectrometry and one-/ two-dimensional nuclear magnetic resonance studies on isolated fractions led to the identification of L-theanine,succinic acid,3,4,5-trihydroxybenzoic acid(gallic acid),and(1 R,2R,3R,5S)-5-carboxy-2,3,5-trihydroxycyclohexyl-3,4,5-trihydroxybenzoate(theogallin)as umami-enhancing compounds in the green tea beverage,and it can be shown by sensory studies that these compounds are able to raise the umami intensity of sodium L-glutamate proportionally.