Grated Grana Padano cheese : new hints on how to control quality and recognize imitations

The sensorial and physico-chemical characteristics described in the product specification for most PDO cheeses are inadequate to verify the compliance of cheeses on the market with the registered designation, particularly for grated products. During the past few years, much research has indicated the analytical parameters suitable for distinguishing Grana Padano (GP) from other similar hard cheeses. The characterization of grated GP is currently based on 3 analytical parameters, related to different aspects of cheese processing, which are: (i) the measurement of alkaline phosphatase (ALP) activity, a marker for possible heat treatment applied to milk, in the outermost layer of the cheese, just below the rind; (ii) the identification of specific peptides, that are identified only in the rind, due to the very slow progress of proteolysis in the rind during GP cheese ripening; and (iii) the free amino acid (FAA) composition. In the present study, we developed an extraction method, based on density gradient centrifugation of solubilized cheese, to separate the outermost layer of the cheeses from the rest in grated cheese, and we proposed a simplified criterion to evaluate the "typicalness" of the FAA pattern. The quality control scheme based on ALP activity, detection of specific peptides and FAA pattern was applied to more than 300 samples of marketed grated GP collected over three years, 10% of which were collected outside Italy, and 3c 100 samples of grated generic ("Grana-type") hard cheeses. The results demonstrate that the simultaneous application of the three parameters allows one to distinguish grated GP from similar, non-PDO grated hard cheeses, and to recognize irregular GP cheeses

Verifica della validit\ue0 del quadro degli amminoacidi liberi a 15 anni dalla sua introduzione per la caratterizzazione del Parmigiano-Reggiano

A seguito di alcune modifiche apportate al disciplinare di produzione, in particolare ai criteri di classificazione merceologica, \ue8 stato verificato che i campioni di Parmigiano-Reggiano di qualit\ue0 scelta vengono riconosciuti come conformi dal modello chemometrico basato sugli amminoacidi liberi

Indagine sulla composizione in amminoacidi liberi del formaggio Provolone quale possibile elemento caratterizzante

Viene studiata la possibilit\ue0 di creare modelli chemometrica atti a tipizzare il formaggio Provolone, determinandone il quadro in amminoacidi liberi ed elaborando statisticamente I dati. Sono state analizzate complessivamente 53 forme di Provolone, sia di et\ue0 ed origine note che del commercio, e sono stati utilizzati criteri di elaborazione statistica descrittiva ed analisi delle componenti principali. Diversamente a quanto riscontrato per il formaggio Parmigiano-Reggiano, il contenuto quali-quantitativo in amminoacidi liberi del Provolone si dimostra molto variabile anche per forme della medesima et\ue0 e di uguali caratteristiche merceologiche (pezzatura, prodotto dolce o piccante), tanto che non si evidenzia alcun modello chemometrico capace di tipizzare questo formaggio sulla base del suo pattern amminoacidico. S\u2019intravede tuttavia la possibilit\ue0 di valutare il periodo di maturazione di forme della medesima pezzatura e di caratterizzare la produzione di determinati caseifici, sulla base del contenuto totale in amminoacidi liberi espresso sulle proteine totali e del contenuto relativo di alcuni di essi quali Glutammina, Istidine, Arginia e Acido gamma-Amminobutirrico. Analisi statistica descrittiva ed analisi delle componenti principali conducono alle medesin\uecme conclusioni, confermando che la tipizzazione chimico-analitica del formaggio Provolone, e dunque la sua difesa da produzioni similari, sar\ue0 possibile solo quando uno standard di qualit\ue0 preciser\ue0 caratteristiche merceologiche e condizioni di lavorazione di questo tipico formaggio italiano.An attempt was made to create chemometric models characterizing Provolone cheese by determining its free amino acid (aa) pattern and evaluating the data with different statistic criteria. 12 commercial samples sold as \u201cProvolone\u201d and 41 typical Provolone cheeses of known age and origin, obtained from dairies under control of the \u201cConsorzio per la Tutela del Formaggio Provolone\u201d were analyzed for their free aa content. Statistical evaluation of the data and related graphic models are presented Unlike Parmigiano-Reggiano, Provolone cheese, even at a same ripening period, shows great variability both in free aa content and in their relative ratios, due mainly to differences in the commercial quality, but probably also to different processing and ripening conditions. Therefor no analytical models based on free aa composition and capable to characterize Provolone cheese can be presently suggested. Nevertheless, parameters based on the total free aa content, expressed as percentage of total protein, and on the relative contents of single free aa like GLN, HIS, ARG, GABA allow both to estimate approximately the ripening period of Provolone cheeses of the same size and to characterize the production of single dairies

Proteolysis indices related to cheese ripening and typicalness in PDO Grana Padano cheese

Different chemical indices related to proteolysis and ripening time have been investigated in Grana Padano (n = 155) and Parmigiano-Reggiano (n = 27) cheese samples using ion-exchange chromatography and capillary electrophoresis. Levels of intact caseins, g-casein and free amino acids in cheese were not strictly related to the maturation period, varying among samples of the same age. A peptide, identified by HPLC/electrospray ionization-mass spectrometry as pyroglutamyl-g3-casein, resulted from cyclisation of N-terminal glutamic acid into a pyroglutamic acid residue. Based on the peak area ratio of pyroglutamyl-g3-casein and g3-casein, an equation, suitable for determination of the cheese age, is proposed. The commercial classes of Grana Padano ripened over 16 and 20 months can be identified by adopting a minimum threshold value for this peak area ratio