Explain the drawback of protein hydrolysates

The drawback of many protein hydrolysates, is that when hydrolysed, most of the food proteins liberate bitter  tasting peptides, which affect their acceptability in certain applications. The bitterness is associated with their mean hydrophobicity. The intensity of bitterness depends on the amino acid composition and sequence and the type of protease used. Hydrolysates of hydrophilic proteins, such as gelatin; are less bitter  than the hydrolysates of  hydrophobic proteins, such as casein and soya proteins.  Protease that show specificity for cleavage at hydrophobic residues, produce hydrolysates that are less bitter than those enzymes which have a broader specificity. Thus, thermolysin, which specifically attacks the amino side of hydrophobic residues, produces hydrolysates that are less bitter than those  produced by low specificity trypsin, pepsin and chymotrypsin.