Identification and taste characteristics of novel umami and umami-enhancing peptides separated from peanut protein isolate hydrolysate by consecutive chromatography and UPLC-ESI-QTOF-MS/MS.

Six novel peptides were separated from peanut protein isolate hydrolysate (PPIH) using ethanol precipitation and gel chromatography, and identified as DQR, NNP, EGF, EDG, TESSSE and RGENESEEEGAIVT by UPLC-ESI-QTOF-MS/MS. On the basis of sensory results, all peptides were perceived umami with threshold values from 0.39 to 1.11 mM and had umami-enhancing abilities simultaneously with threshold values from 0.33 to 0.82 mM. RGENESEEEGAIVT was the first discovered tetradecapeptide with umami and umami-enhancing ability. The dose-response test revealed that umami-enhancing activities of identified peptides were different: TESSSE and RGENESEEEGAIVT imparted better umami intensity when equimolar monosodium glutamate (MSG) was added into 0.5 g/L MSG solution. Taste profile analyses of complex mixtures with/without synthetic peptides were determined by both electronic tongue and human panellists, suggesting that umami peptides influence multiple tastes and electronic tongue has the potential to replace sensory test to distinguish taste attributes of foods rich in peptides.