title: Discovery of kokumi peptide from yeast extract by LC-Q-TOF-MS/MS and sensomics approach.
abstract: BACKGROUND
  Yeast extract can impart thickness, complexity and long-lasting taste impression, coined kokumi taste, to blank chicken broth. In this research, the kokumi-active peptide in yeast extract was discovered by ultrafiltration, liquid chromatographic and quadrupole-time-of-flight-tandem mass spectrometric technologies. Furthermore, the sensory characters of these peptides were evaluated by a sensomics approach.
  
  
  RESULTS
  A total of 10 kokumi peptides were identified from yeast extract. They were γ-Glu-Cys-Gly, γ-Glu-Leu, γ-Glu-Val, γ-Glu-Tyr, Leu-Lys, Leu-Gln, Leu-Ala, Leu-Glu, Leu-Thr and Ala-Leu. Apart from the well-known kokumi-active glutathione and γ-glutamyl dipeptides, five leucyl dipeptides were first proposed having kokumi activity. Among them, Ala-Leu was found to have the highest kokumi threshold concentration (1.5 mmol L(-1) ) in the blank chicken broth, while Leu-Glu was the lowest (0.3 mmol L(-1) ). A subsequent dose-response experiment indicated that the bitter-tasting leucyl dipeptides could impart kokumi taste to chicken broth at low concentrations (less than bitter threshold concentrations). Interestingly, the kokumi sensation began to decrease when such peptides exceeded the threshold concentration by approximately 16-fold in the blank chicken broth.
  
  
  CONCLUSIONS
  Key kokumi-active fractions were purified from yeast extract. Among them, ten important kokumi peptides from yeast extract were identified.
authors.affiliation: Laboratory of Molecular Sensory Science, Beijing Technology and Business University, Beijing, 100048, China.
authors.forename: Jianbin
authors.initials: J
authors.lastname: Liu
authors.affiliation: Laboratory of Molecular Sensory Science, Beijing Technology and Business University, Beijing, 100048, China.
authors.forename: Huanlu
authors.initials: H
authors.lastname: Song
authors.affiliation: Laboratory of Molecular Sensory Science, Beijing Technology and Business University, Beijing, 100048, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Yeast Extract Seasoning Division, Angel Yeast Co. Ltd, Yichang, Hubei, China.
authors.forename: Pei
authors.initials: P
authors.lastname: Li
authors.affiliation: Yeast Extract Seasoning Division, Angel Yeast Co. Ltd, Yichang, Hubei, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Yao
authors.affiliation: Yeast Extract Seasoning Division, Angel Yeast Co. Ltd, Yichang, Hubei, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Xiong
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D000818:Animals; D002645:Chickens; D002853:Chromatography, Liquid; D005421:Flavoring Agents / Q000032:analysis*; D006801:Humans; D008460:Meat; D010446:Peptide Fragments / Q000302:isolation & purification; D010455:Peptides / Q000302:isolation & purification*; D053719:Tandem Mass Spectrometry; D013649:Taste; D015003:Yeasts / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D005421:Flavoring Agents; D010446:Peptide Fragments; D010455:Peptides
keywords: LC-Q-TOF-MS/MS; kokumi; peptide; sensomics approach; yeast extract