De. Stevenson et al., PROTEASE-CATALYZED CONDENSATION OF PEPTIDES AS A POTENTIAL MEANS TO REDUCE THE BITTER TASTE OF HYDROPHOBIC PEPTIDES FOUND IN PROTEIN HYDROLYSATES, Enzyme and microbial technology, 22(2), 1998, pp. 100-110
Synthetic dipeptides of varying hydrophobicity were used as a model sy
stem to investigate the feasibility of reversed protease action as a m
eans of improving the flavor of bitter peptides found in protein hydro
lysates. The four different proteases tested were able to convert hydr
ophobic dipeptides into an insoluble precipitate, but with different e
fficiencies. Hydrophilic dipeptides did not give detectable condensati
on or precipitation. Solid-state and solution NMR were used to monitor
peptide bond formation in C-13-labelled peptides. NMR and MS analyses
showed that the products consisted of higher oligomers of the origina
l peptide. Bitterness decreased in the order starting with dipeptides
> whole reaction mixtures >> isolated precipitates. Taste improvement
correlated with peptide bond formation and the formation of insoluble
material. These observations indicated that the condensation reaction
was driven by precipitation of insoluble reaction products and that th
is process is a potential means to improve the flavor of bitter peptid
es extracted from protein hydrolysates. (C) 1998 Elsevier Science Inc.