Bitter-tasting hydrophobic peptides prepared from soy sauce using aqueous ethanol solutions influence taste sensation

In this study, bitter-tasting hydrophobic peptides were prepared and purified from soy sauce using aqueous ethanol solutions and ion exchange resin, and analysed using RP-HPLC and UPLC-Q-TOF-MS/MS. Most of bitter fraction from soy sauce was obtained by treatments involving 80% ethanol and subsequent chromatographic separation. This fraction contained sixteen small peptides (molecular weight < 1000 Da; rich in hydrophobic amino acids with Lys-Pro (KP), Glu-Phe (EF), Glu-Val (EV), Asp-Leu (DL), Leu-Trp (LW) and Asp-Pro (DP)) capable of enhancing significantly (P < 0.05) umaminess and/or imparting kokumi effect in taste reconstitution experiments. Thus, the bitter peptides affected bitterness as well as other taste sensations like umaminess, kokuminess and saltiness. This was the first study to report the impacts of the bitter-tasting hydrophobic peptides on soy sauce and solutions of salt, monosodium l-glutamate.