The proteolysis of β-casein (CN) by action of plasmin characterizes the ripening of several cheeses, and one of the newly formed peptides, pyroglutamyl-g3-CN (pg3-CN), originates from the cyclization of the N-terminal Glu of g3-CN (β-CN f108-209). This peptide revealed in both Grana Padano PDO and Parmigiano-Reggiano PDO cheeses 2 months after manufacture progressively increased in content during ripening. A preliminary survey revealed pg3-CN in both hard and extra-hard cheese varieties, whereas in semi-hard cheeses it was present only in mature samples. To understand the mechanisms of pg3-CN formation/degradation, in vitro trials (real cheese, model cheeses and buffered g3-CN solutions) were performed. Both the effect of cheese pH and the capacity of selected microorganisms (L. helveticus, E. faecalis and E. faecium) to cyclize the N-terminal Glu residue of g3-CN were studied. The results suggested that while pg3-CN formed spontaneously during cheese ripening, mainly at the acid pH characteristic of hard and extra-hard cheeses, the role of cyclase enzymes was negligible. Differences in pg3-CN degradation were observed, due to the proteolytic activity of bacteria involved in the cheese ripening.
Occurrence, origin and fate of pyroglutamyl-γ3-casein in cheese / F. Masotti, I. De Noni, S. Cattaneo, M. Brasca, V. Rosi, M. Stuknyte, S. Morandi, L. Pellegrino. - In: INTERNATIONAL DAIRY JOURNAL. - ISSN 0958-6946. - 33:2(2013), pp. 90-96. [10.1016/j.idairyj.2013.06.002]
Occurrence, origin and fate of pyroglutamyl-γ3-casein in cheese
F. MasottiPrimo
;I. De NoniSecondo
;S. Cattaneo;V. Rosi;M. Stuknyte;L. PellegrinoUltimo
2013
Abstract
The proteolysis of β-casein (CN) by action of plasmin characterizes the ripening of several cheeses, and one of the newly formed peptides, pyroglutamyl-g3-CN (pg3-CN), originates from the cyclization of the N-terminal Glu of g3-CN (β-CN f108-209). This peptide revealed in both Grana Padano PDO and Parmigiano-Reggiano PDO cheeses 2 months after manufacture progressively increased in content during ripening. A preliminary survey revealed pg3-CN in both hard and extra-hard cheese varieties, whereas in semi-hard cheeses it was present only in mature samples. To understand the mechanisms of pg3-CN formation/degradation, in vitro trials (real cheese, model cheeses and buffered g3-CN solutions) were performed. Both the effect of cheese pH and the capacity of selected microorganisms (L. helveticus, E. faecalis and E. faecium) to cyclize the N-terminal Glu residue of g3-CN were studied. The results suggested that while pg3-CN formed spontaneously during cheese ripening, mainly at the acid pH characteristic of hard and extra-hard cheeses, the role of cyclase enzymes was negligible. Differences in pg3-CN degradation were observed, due to the proteolytic activity of bacteria involved in the cheese ripening.File | Dimensione | Formato | |
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