Studies of bitter peptides from casein hydrolyzate. Part XII. Bitter taste of H-Pro-Phe-Pro-Gly-Pro-Ile-Pro-OH corresponding to the partial sequence (positions 61-67) of bovine .BETA.-casein, and related peptides.

Abstract

The bitter components of cheese are hydrophobic peptides which are produced during the process of enzymatic digestion, and some of the isolated bitter peptides are derived from the middle portion of β-casein. However, quantitative examination of the bitter taste is seldom performed. We synthesized two hydrophobic peptides, H-Pro61-Phe-Pro-Gly-Pro-Ile-Pro67-OH and H-Tyr60-Pro-Phe-Pro-Gly-Pro-Ile66-OH, which correspond to common portions among the isolated bitter peptides, in order to determine how bitter they were. From the results of sensory analysis, it was found that the synthetic peptides exhibited a bitter taste with threshold values 0.25 and 0.16mm, respectively. We also synthesized their fragments and analogs, and discussed the structure-bitterness relationship.