Separation and identification of hydrophilic peptides in dairy products using FMOC derivatization

Small hydrophilic di- and tripeptides from food products are not separated by reversed-phase high-performance liquid chromatography (RP-HPLC). A simple method using precolumn derivatization with 9-fluorenylmethoxycarbonyl chloride (FMOC) of hydrophilic peptides followed by RP-HPLC separation is presented. Peptides can subsequently be identified by Edman degradation after deprotection of the peptide derivatives with piperidine. Fifteen peptides (ten dipeptides, four tripeptides and one tetrapeptide) were sequenced from the water-soluble fraction of an enzyme-modified cheese model. Some synthetic peptides (Ile-Asn, Val-Thr, Ala-Pro, Val-Gln, Thr-Gln and Gly-Gly) corresponding to purified peptides were sensory tested.