On The Possibility to Trace Frozen Curd in Buffalo Mozzarella Cheese

The manufacturing of Buffalo Mozzarella PDO (Protected Designation of Origin) cheese requires the exclusive use of fresh buffalo milk, which must be transformed into cheese within 60 hours after milking. The limited availability of buffalo milk and simultaneous increase in Mozzarella demand during the summer cause producers to use frozen intermediates (milk and/or curd) in the cheese-making process. These practices are not allowed. Few data are available in the literature about the effects of freezing on buffalo milk and curd. Recent studies demonstrated that the use of frozen buffalo milk can be detected in mozzarella cheese based on the increase in casein fragment γ4-CN. This work aims to verify the possibility of tracing the presence of frozen curd in Buffalo Mozzarella PDO cheese. The electrophoresis technique was used to reveal the presence of γ4-CN. Equivalent concentrations of this fragment were found in fresh and frozen curd that were stored for 9 months. Our results suggest that γ4-CN cannot be used to discriminate fresh PDO Mozzarella and Mozzarella cheese produced from frozen curd. A second objective of the work was to evaluate the effects of freezing on curd lipids. In particular, the fatty acid and mono-diglyceride profiles were evaluated. Significant differences were found in the amounts of 1,2-Dipalmitin and 1,3-Diolein between fresh curd and curd that was stored for 9 months at freezing temperatures. Although some significant differences were found in the mono-diglyceride profiles, no objective marker that can distinguish between fresh and frozen products is currently available

On the possibility to trace frozen curd in Buffalo Mozzarella PDO cheese

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

Performance of a protein extracted from potatoes for fining of white musts

In this study, the potentiality of Patatin (P), a protein extracted from potato, as must fining agent was investigated on musts obtained from two South Italy grape cultivars (Falanghina and Greco). Besides P, fining agents as bentonite (B) and potassium caseinate (C) were assayed at different concentrations. The rate of sedimentation, the decline of turbidity during time, the absorbance at 420 nm, the GRP (grape reaction products) and hydroxycinnamic acids (HCA) concentrations were determined. The comparative trials showed that P is a suitable fining agent to prevent browning and decrease haze during must settling because its effect on grape phenolics, brown pigments and turbidity is comparable and/or better than that detected for C. Its use as single fining agent or in combination with B depends on must characteristics

The effects of probiotics and prebiotics on the fatty acid profile and conjugated linoleic acid content of fermented cow milk

The ability of probiotic bacteria (Lactobacillus acidophilus La5 and Bifidobacterium animalis Bb12), to produce conjugated linoleic acid (CLA) in association with Streptococcus thermophilus and Lb. bulgaricus during milk fermentation has been evaluated in this study. Pasteurized cow milk and infant formula were used. Infant formula was selected for its high linoleic acid content, for being a source of CLA and for its prebiotic compounds, e.g. galacto-oligosaccharides. The microorganisms were not able to increase the CLA content of the fermented products under the given experimental conditions. No statistically significant differences (p>0.05) occurred between the CLA content in milk and the fermented samples. The CLA contents of 10 commercial fermented milk products were determined. The highest CLA content was observed in fermented milk containing only Str. thermophilus and Lb. bulgaricus. © 2015 Informa UK Ltd. All rights reserved