Unraveling bitter peptides in wheat protein hydrolysates

Abstract

Wheat protein hydrolysates (WPHs) hold promise for functional food applications, but papain (EC 3.4.22.2)-mediated hydrolysis often results in undesirable bitterness and low yields of small peptides. To address this, we employed in silico strategies to systematically characterize bitter peptides in papain-derived WPHs and elucidate their molecular interactions with the human bitter taste receptor TAS2R14. Enzymatic hydrolysis of wheat proteins was simulated using the BIOPEP-UWM database, identifying 36 potential bitter peptides. Molecular docking studies revealed four critical binding residues (Asn157, Ile262, Trp89, and Phe247) on TAS2R14 that mediate bitterness perception. Notably, peptides rich in proline (Pro), phenylalanine (Phe), and tryptophan (Trp) exhibited heightened bitterness, while glycine (Gly)- and glutamic acid (Glu)-containing peptides were associated with reduced bitterness. These findings provide a mechanistic basis for mitigating bitterness in WPHs through selective enrichment or exclusion of peptides with specific amino acid profiles. By enabling targeted design of hydrolysis processes, this work advances the application of WPHs as palatable, bioactive ingredients in the food industry.

Keywords: ADMET; Bitterness; In silico; Molecular docking; TAS2R14; ToxinPred.

Computer enzyme hydrolysis simulation, activity prediction, TAS2R14 receptor binding mechanism.

Fig. 1

Classification of wheat protein fractions and structures.

Fig. 2

Molecular docking of the 36 bitter peptides with bitter taste receptor (TAS2R14). Note: (Left) The 3D hydrogen bond surface plot at the binding site. (Right) The 2D diagram of the docking of the bitter peptide with TAS2R14. The abbreviation indicates 35 dipeptides and one tripeptide shown in Table 3, accordingly.

Fig. 2

Molecular docking of the 36 bitter peptides with bitter taste receptor (TAS2R14). Note: (Left) The 3D hydrogen bond surface plot at the binding site. (Right) The 2D diagram of the docking of the bitter peptide with TAS2R14. The abbreviation indicates 35 dipeptides and one tripeptide shown in Table 3, accordingly.