Identification of yak whey protein-derived peptides as novel blockers of metal ion-induced bitterness

Metal ions are widely existed in food and medicine, however, few researches study the solution for suppresing the bitterness induced by metal ions. In this study, Fe was selected as a representative metal ion for screening bitter-inhibiting peptides due to its exceptionally low taste threshold. Yak whey protein hydrolytes (YWPHs) were screened for inhibitors of bitterness induced by ferrous sulfate. After fractionation via dextran gel column and RP-HPLC chromatography, subfraction T1 showed the highest inhibitory effect on bitterness evaluated by E-tongue. T1 exhibited strong chelating ability with ferrous sulfate (59.6 ± 0.3 %). Peptides derived from T1 were futher screened for high chelation rate with Fe 2+ through affinity chromatography and a total of 12 peptides were identified as potential bitterness blockers. Among them, five peptides (SSPP, HPR, QPP, RLLPKAP, TESLEPLQGAV) with the highest chelation rate were synthesized and validation test demonstrated that their chelating ability and bitterness-inhibitory activity were all significantly higher than that of lactoferrin (LF). Sensory evaluation indicated that trypsin hydrolysates of YWHPs (MW < 5 kDa) effectively decreased the bitterness intensity of FeSO 4 solution. Novel blockers found in this study showed a promising application in eliminating the bitterness induced by metal ions in food and pharmaceutical industry. • Novel blockers of metal ion-induced bitterness were identified from yak whey. • Five peptides demonstrated the strongest Fe 2+ chelation capacity and bitter-masking activity. • Sensory evaluation confirmed TH-YWHPs decreased the bitterness induced by FeSO 4 solution. • Novel blockers showed promising application in food and pharmaceutical industry.