Chromatographic Isolation of Presumptive Peptide Flavor Principles from Red Meat

Abstract

Top round, bovine semimembranosus and adductor muscle was selected as a model for isolation of presumptive, low molecular mass (M_r) flavor peptides. The isolation and purification of these peptides (<5,000 M_r) from ‘cooked’ and ‘cooked-stored-recooked’ meat was developed by combining various chromatographic techniques. Peptide samples were initially made by preparing acetic acid extracts of meat followed by the removal of organic soluble lipids and carbohydrates by phase partition extraction. The lipid-free extracted material was subsequently subjected to size exclusion chromatography using Sephadex G-25 resulting in two major polypeptide groups with M_r of 1500 to 3000. This material was now available for further purification by both semipreparative and analytical reverse phase (RP) - high performance liquid chromatography (HPLC) for separation of hydrophilic and hydrophobic peptides. Separation of the peptides into these two groups is particularly important since the perception of sweet taste is usually associated with hydrophilic peptides while bitter (and often sour) taste is associated with hydrophobic peptides. Semipreparative RP-HPLC of peptides from the low M_r material revealed highly significant differences in the hydropilic and hydrophobic peptide composition of ‘cooked’ versus ‘cooked-stored-recooked’ samples i.e., the former appeared to have equal amounts of the two classes of peptides while the latter appeared to contain predominantly hydrophobic peptides. Peptides prepared semipreparatively were readily available for further examination by analytical RP-HPLC and analyzed by diode array detection. The latter method revealed major differences in the hydrophobic peptide components found in the two meat groups.