The effectiveness of packing media differing in the content of natural antioxidants has been tested on lipid oxidation occurring during tuna canning. Extra virgin olive oil, having a high content in natural polyphenols, and other filling media lacking phenols (refined olive oil, refined soybean oil, and brine) were selected. The three oils also showed different quantities of tocopherols, the highest amount being detected in refined soybean oil. Different rates of oxidation were observed among the four media after thermal processing and storage of tuna cans; extra virgin olive oil showed a potential antioxidant activity on fish lipids. The verified antioxidant ability may be attributed to the solubilization of hydrophilic phenols into the water−muscle interface. The phenolic composition from extra virgin olive oil studied by reversed-phase HPLC showed a marked change after fish processing, thus suggesting phenol decompositions and strong interactions between oil phenols and fish muscle components. The aqueous environment built by brine made fish lipids more prone to oxidation, presumably due to the accumulation of unsaturated fatty acids at the oil−water interface. Keywords: Antioxidants; fish lipid oxidation; canning; packing medium (extra virgin olive oil, refined olive oil, soybean oil, brine); phenols

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.

Buffalo mozzarella cheese is one of the most appreciated traditional Italian products and it is certified as a Protected Designation of Origin (PDO) product under the European Commission Regulation No. 1151/2012. It is obtained exclusively from buffalo milk. If made from cow milk, or a mixture of buffalo and cow milk, buffalo mozzarella cheese does not qualify as a PDO product. In order to maximize their profits, some producers market buffalo mozzarella that also contains cow milk as a PDO product, thus defrauding consumers. New methods for revealing this fraud are therefore needed. One such method is the droplet digital Polymerase Chain Reaction (ddPCR). Thanks to its high precision and sensitivity, the ddPCR could prove an efficacious means for detecting the presence of cow milk in buffalo mozzarella cheese that is marketed as a PDO product. ddPCR has proved able to detect the DNA of cow and/or buffalo milk in 33 buffalo mozzarella cheeses labelled as PDO products, and experimental evidence could support its application in routine analyses.

Buffalo Mozzarella cheese from Campania is one of the most worldwide appreciated Italian dairy products. The increased demand for buffalo dairy products and the limited availability of the finest buffalo milk has prompted the diffusion of illicit practices, such as the use of milk, curd, or other products that are frozen or bought at low cost. The aim of this research was to provide preliminary results about the trend of the microbial communities of buffalo milk, curd and Buffalo Mozzarella cheese, during freezing storage of eleven months. At the same time, the alterations of physical properties and the presence of the molecular marker “γ4-casein”, have been investigated. The results showed that freezing reduced the concentrations of the total bacterial count, Enterobacteriaceae, coliforms, Escherichia coli and yeasts in fresh milk and, the concentrations of the total bacterial count, coliforms, lactic acid bacteria and yeasts in mature curd. In the finished product, no notable decreases were observed, except for lactic acid bacteria. About the γ4-casein, no increase was observed in all matrices. These preliminary results allow us to conclude that the freezing process if properly carried out, does not compromise the microbiological quality and the physical properties of the Buffalo Mozzarella cheese.

Campania’s buffalo mozzarella is a greatly appreciated cheese in Italy and worldwide. From a microbiological standpoint, it is a highly perishable food and potentially at risk of contamination by pathogens such as Listeria monocytogenes (L. monocytogenes). The present paper reports the results of a challenge test carried out to assess the population dynamics of L. monocytogenes, alone and in presence of Pseudomonas fluorescens (P. fluorescens), in buffalo mozzarella. For this purpose buffalo mozzarella samples were contaminated with L. monocytogenes alone or combined with P. fluorescens. In samples where L. monocytogenes was inoculated alone, the bacterial load remained unchanged. On the contrary, in samples contaminated with L. monocytogenes and P. fluorescens, the growth of L. monocytogenes increased.