Characterization of the oligopeptides of Parmigiano-Reggiano cheese soluble in 120 g trichloroacetic acid/l.
The non-protein nitrogen (NPN) of samples of Parmigiano-Reggiano cheese ripened for 6 and 15 months was fractionated by ion-exchange chromatography on a Cu(2+)-Chelex column to separate oligopeptides from free amino acids. Peptide components were isolated by reversed-phase HPLC and identified by fast atom bombardment-mass spectrometry (FAB-MS). Only the NPN fraction of 6 month old cheese samples contained enough peptides to be further characterized. On the basis of FAB-MNS spectral results, 39 oligopeptides were identified, the main components being phosphopeptides. Two sets of both intact and partly dephosphorylated peptides, accounting for a total of 19 phosphopeptides, were formed by the hydrolysis of beta-casein and belonged to regions 1-20 and 6-28 of beta-casein. The formation and potential role of these peptides in cheese is discussed.
Dipartimento di Scienza degli Alimenti, Università di Napoli Federico II, Portici (NA), Italia.
F
F
Addeo
L
L
Chianese
R
R
Sacchi
S S
SS
Musso
P
P
Ferranti
A
A
Malorni
D000595:Amino Acid Sequence; D002611:Cheese / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009842:Oligopeptides / Q000032:analysis* / Q000737:chemistry; D010748:Phosphopeptides / Q000032:analysis / Q000737:chemistry; D016339:Spectrometry, Mass, Fast Atom Bombardment
D009842:Oligopeptides; D010748:Phosphopeptides