Manzo, Nadia (2017) On the possibility to trace frozen curd in Buffalo Mozzarella PDO cheese. [Tesi di dottorato]

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Tipologia del documento: Tesi di dottorato
Lingua: English
Titolo: On the possibility to trace frozen curd in Buffalo Mozzarella PDO cheese
Autori:
AutoreEmail
Manzo, Nadianadia.manzo@unina.it
Data: 6 Aprile 2017
Numero di pagine: 133
Istituzione: Università degli Studi di Napoli Federico II
Dipartimento: Agraria
Dottorato: Scienze agrarie e agroalimentari
Ciclo di dottorato: 29
Coordinatore del Corso di dottorato:
nomeemail
D'Urso, Guidodurso@unina.it
Tutor:
nomeemail
Romano, Raffaele[non definito]
Data: 6 Aprile 2017
Numero di pagine: 133
Parole chiave: buffalo mozzarella cheese, PDO, freezing
Settori scientifico-disciplinari del MIUR: Area 07 - Scienze agrarie e veterinarie > AGR/15 - Scienze e tecnologie alimentari
Depositato il: 06 Mag 2017 14:19
Ultima modifica: 14 Mar 2018 09:26
URI: http://www.fedoa.unina.it/id/eprint/11525
DOI: 10.6093/UNINA/FEDOA/11525

Abstract

Campana Buffalo Mozzarella PDO (Protected Designation of Origin) is a stretched curd cheese produced exclusively by using fresh buffalo milk, which must be processed within 60 hours after milking (EC Regulation 103/2008). According to PDO specification, the cheese must satisfy certain criteria, such as white porcelain color, fat/dry matter ≥ 52% (w/w) and maximum moisture content 65% (w/w). This certification represents a guarantee of quality for both producers and consumers, in terms of safety, genuineness and freshness. However, the high consumer’s cheese demand, the limited amount of available buffalo milk, and the high market price, make mozzarella cheese a remunerative target for either adulterated or false PDO sales. It is known that buffalo milk production changes with a seasonal trend. During the summer there is a limited availability of buffalo milk and a concurrent increase in Buffalo Mozzarella PDO demand. To overcome this inconvenience, producers resort to practices which are not contemplated in the specification. In particular, they freeze milk or curd (mainly curd) in the winter and use them to manufacture Mozzarella when there is a lack of fresh milk. Moreover, some producers buy frozen curd from foreign countries at low costs and mix it with the local curd to produce PDO cheese. Food control authorities require, therefore, analytical methods to discriminate between fresh Mozzarella PDO cheese and Mozzarella produced from frozen intermediates, which are not produced according to the PDO manufacturing process. The aims of this work were to assess the chemical and structural modifications that may occur during the freezing of cheese intermediates and to evaluate mozzarella cheese quality obtained by frozen curd. Firstly, markers of freshness identified in scientific literature (γ4-CN and αs1-I CN) were evaluated. According to our results, γ4-CN was not effective to discriminate mozzarella cheese produced by frozen milk or curd, since keeping samples at freezing temperatures for 9 months, no significant difference was found in the γ4-CN content respect to the fresh samples. The fragment αs1-I CN was also found not efficient in evaluating conformity to PDO, since it was not detected in any analysed samples. The study of lipids demonstrated no significant differences in fatty acid and triglycerides profiles after freezing storage, while mono-diglycerides, examined as an index of lipolytic activity, showed an increase after a freezing period of 9 months. The differential scanning calorimetry showed significant differences in the enthalpy of fat extracted by mature curd after 9 months of storage at -20°C. With increasing percentage of frozen curd in the cheese, different melting and crystallization profiles were observed for fresh mozzarella cheese and mozzarella obtained by frozen curd. Moreover, a reduction of melting temperature was observed. By a structural point of view, the increase in frozen curd addition led to a harder texture of mozzarella cheese. X-Ray analysis revealed a spongy texture of the fresh product and allowed to discriminate fresh mozzarella, characterized by higher presence of voids, from mozzarella made with frozen curd. Although the results were preliminary, the analysis based on both low- and high-resolution NMR seemed to be a useful approach to detect fraudulent addition of frozen curd in Buffalo Mozzarella PDO cheese. Differences were also found in protein and peptide profile of Mozzarella cheese soluble fraction and in peptide pattern after simulated gastrointestinal digestion. A full structural identification of cheese peptides could lead to the identifications of molecular marker effective for discriminating the different products.

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