Structural Characteristics of Food Protein‐Derived Bitter Peptides

Certain amino acid sequences encoded within the primary structure of food proteins impart no bitter taste when present as structural components of native proteins. However, upon release from the native (mother) protein during chemical or enzymatic hydrolysis, the free peptide has a bitter taste when ingested orally. Bitterness intensity of the peptide is related to ability to interact with bitter taste receptors (T2Rs) in the oral cavity. Ability of a peptide to elicit bitter taste is dependent on amino acid composition, specifically an abundance of hydrophobic residues. Arrangements of the amino acids also influence bitterness intensity because basic residues at the N-terminal and hydrophobic or bulky residues at the C-terminal are preferred. Most influential amino acids for increased bitterness intensity are proline, valine, leucine, phenylalanine and tryptophan. However, spatial structure is also important, especially short distances between N- or C-terminal C=O group and hydrophobic groups promote stronger bitterness intensity. In this chapter, other structural properties required for bitterness intensity as well as methods for decreasing or removing peptide bitterness are discussed.