Structural characteristics of food protein-originating di- and tripeptides using principal component analysis

This paper presents the use of principal component analysis (PCA) to study the effect of specific physicochemical attributes on bitterness of di- and tripeptides originating from food proteins. Peptide sequences were derived from the BIOPEP-UWM database of sensory peptides and amino acids. Descriptors defining the physicochemical properties of amino acids forming the analyzed peptides were study variables. They were derived from ProtScale program and Biological Magnetic Resonance Data Bank. Finally, PCA was carried out for 51 dipeptides/12 variables, and 51 tripeptides/18 variables using STATISTICA®13.1 software. PCA allowed reducing the input datasets to 4 principal components (PCs) for dipeptides and to 5 PCs for tripeptides. The impact of the following properties on the bitterness of peptides was observed: relatively high molecular weight, bulkiness, increasing number of carbon and hydrogen atoms of amino acids forming the sequences. These properties characterized the N- (negative correlations) and C-terminal residue (positive correlations) of both di- and tripeptides. An additional property affecting peptide bitterness was amino acids' hydrophobicity. Our results were consistent with scientific reports on structure–bitterness of peptides. Thus, we find PCA a chemometric approach helpful in broadening the knowledge about the function of peptides resulting from their chemical nature.