Isolation and Identification of Some Major Water-soluble Peptides in Feta Cheese

Peptides were isolated from the water-soluble fraction of Feta cheese by reversed-phase HPLC in three successive steps. Peptide sequencing was performed by automatic Edman degradation. Most of the peptides originated from alpha s1-casein (CN), especially from the N-terminal half of the molecule. Two peptides originated from the C-terminal domain of beta-CN. Only one peptide, which was rich in histidine, originated from kappa-CN. beta-Lactoglobulin and alpha-lactalbumin were also identified in the water extract of Feta cheese. The origin of most of these peptides could be explained on the basis of known specificities of chymosin and lactococcal cell-wall proteinases.