Study of the oligopeptide fraction in Grana Padano and Parmigiano-Reggiano cheeses by liquid chromatography electrospray ionization mass spectrometry

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Eur. J. Mass Spectrom. DOI: 10.1255/ejms.603

Study of the oligopeptide fraction in Grana Padano and Parmigiano-Reggiano cheeses by liquid chromatography electrospray ionization mass spectrometry

Stefano Sforza, Gianni Galaverna, Arnaldo Dossena and Rosangela Marchelli
Department of Organic and Industrial Chemistry, University of Parma, Parco Area delle Scienze 17/a, I-43100, Parma, Italy
Erasmo Neviani
Department of Genetic Antropology Evolution, Laboratory of Food Microbiology, University of Parma, Parco Area delle Scienze, I-43100, Parma, Italy
Costante Pinelli
Parmalat S.p.A., I-43044, Collecchio, Parma, Italy

ABSTRACT:

The oligopeptide fractions of Grana Padano and Parmigiano Reggiano cheese samples at various stages of aging (6, 12, 18 and 24 months) were analysed by means of HPLC coupled to electrospray (ESI) MS. The main oligopeptides (<5000Da) present in the samples were extracted by using an originally developed method which allowed good enrichment of the oligopeptide fractions and identified according to their molecular weights. The casein sequences compatible with the found molecular weights were determined and the exact oligopeptide sequences were identified by using the fragmentation peaks originated by in-source collisionally induced dissociation (CID). The ESI-MS method here reported allowed the sequence identification of oligopeptides in a very fast way by a single LC-MS run. Oligopeptides were also semi-quantified by comparison with a suitable internal standard (the dipeptide phenylalanylphenylalanine, Phe-Phe). This methodology demonstrated that, as far as the main oligopeptides are concerned, Grana Padano and Parmigiano Reggiano presented very similar composition. Anyway, the evolution of the fractions during aging time was characteristically distinct among the two cheeses: in Grana Padano cheeses most of the oligopeptides reached a maximum at 12 months of aging and then decreased, whereas in Parmigiano Reggiano cheeses the oligopeptide amounts were usually lower and had a less regular trend. The reason for this different behaviour may be ascribed to the different technology of production.

Keywords: ESI-MS, Grana Padano, in-source CID, oligopeptides, Parmigiano Reggiano

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