Urbani, Valeria (2015) INFLUENCE OF DIFFERENT SMOKING TECHNIQUES ON CONTAMINATION BY POLYCYCLIC AROMATIC HYDROCARBONS IN TRADITIONAL SMOKED BUFFALO MOZZARELLA. [Tesi di dottorato]

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Abstract

Technological food processing, such as grilling and smoking, can produce high levels of PAH in treated products, and risk for human health is related to the type of ingested food and the frequency of consumption. However, the recent legislation (Regulation EC 835/2011) on maximum levels of PAHs in foods did not set limits for milk and dairy products, including smoked cheeses, even if some smoking techniques can cause formation and accumulation of PAHs on food. Among smoked cheese, smoked buffalo mozzarella or "provola" is a typical product with DOP mark, it may be PAH contaminated. During traditional smoking process Mozzarella was exposed to smoke obtained from the incomplete straw or wood shavings combustion in smoking room. Alternatively, the smoked product is obtained by immersing the cheese in the so-called "liquid smoke", a solution obtained through condensation and filtration of smoke. Sometimes, illegal procedures, as corrugated paper or varnished wood combustion, are employed for smoking food production. The authorized materials are wheat straw, wood shavings of fir, beech or alder bark, which are placed in special containers. This thesis project aimed to assess levels and distribution of B(a)P and other three marker PAHs (PAH4), as suggested by EFSA in the smoked buffalo mozzarella cheese obtained by different smoking techniques usually employed in dairies of Campania. Besides the influence of different techniques, permitted or non by law, on the content of PAHs in mozzarella was evaluated. This research, aimed to study the migration of PAHs from the external surface (rind) of the mozzarella, more exposed to the smoke, into core and so consumer exposure to these contaminants through ingestion of whole mozzarella. For this purpose were analyzed separately out of mozzarella (rind), core and whole product. 50 batches of samples of buffalo mozzarella, each of 16 samples (250 gr), produced according to the specifications established by the Decree (D.Mi.PAF. 2003), in a dairy farm located in the Salerno province (Campania) and with CE mark. Once produced, mozzarella samples were transported to another dairy, where, a mozzarella was not smoked and conceded as blank matrix while groups of three mozzarella were smoked with different techniques such as combustion of cardboard, bark of alder, chips of fir or beech, wheat straw and liquid smoke. The obtained results showed a not PAH contamination in non-smoked mozzarella cheese samples and in the core of smoked ones. About the rind, highest levels were found in sample obtained from cardboard combustion and in particular BaP levels ranged from 110 to 417.8 µg/kg. However, the levels found in traditional techniques were highest in samples obtained by bark of alder combustion (5.1 µg/kg – 54.0 µg/kg), followed by chips of fir or beech combustion (1.5 µg/kg – 44.3 µg/kg) and straw (0.2 µg/kg – 28.2 µg/kg). Considering the whole products, similar trend was observed. In particular, the use of illegal techniques such as cardboard combustion showed highest BaP (median 8.3 µg/kg), while in traditional techniques bark of alder showed a median of 2.8 µg/kg, followed by chips of fir or beech with a median 1.2 µg/kg and finally, by straw with a median of 0.4 µg/kg. All sample obtained by immersion in liquid smoke showed not detectable PAH levels both in rind and in whole product. A statistical analysis was carried out in order to evaluate if the time can effect on the PAH formation, and any statistical differences were found. However the use of different materials and techniques can produce a different amount of PAH in smoked food. A statistical analysis showed that the rind can represent a barrier to migration of generated PAH into the core of the products and it so can support the accumulation of these compounds. For this reason it is recommended to remove the rind until the ingestion of this smoked cheese, considering also that our data are always higher than daily intake and intake for person evaluated by EFSA, except for liquid smoke. This suggests that mozzarella subjected to treatment with liquid smoke is preferable to the those smoked with traditional procedures.

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