Effect of packaging technology on ripening events occurring during storage of portioned PDO Italian semi-hard cheese

The aim of the present study was to assess the ability of the packaging technology (vacuum, VAC, and modified atmosphere, MAP) to preserve the microbiological, physicochemical, and sensorial properties of already ripened and portioned PDO Italian semi-hard cheese during 120 days of storage at 8 degrees C. Results were compared with those obtained by analyzing the original not-packed cylindrical wheel stored at 8 degrees C (NP). Samples packed under MAP showed yeasts' proliferation with a final count of 4.68 Log cfu g(-1), similar to that detected in the NP cheese wheels at 120 days of storage. In VAC samples yeasts did not proliferate, maintaining constant levels during time. Differently from the original wheels which showed a hardness increase in concomitant with a moisture loss during storage, packed samples under both VAC and MAP did not lose water preserving the original hardness of the product. At the same time, the packaging technology did not influence the proteolysis index in comparison to NP cheese. However, in MAP samples already at 30 days of storage different volatile compounds were produced in comparison with NP and VAC cheeses, suggesting that the modified atmosphere into the MAP pack promoted alternative microbial metabolisms and final products characterized by different volatile profiles. The study clearly demonstrated that the choice of packaging technology has an impact on the development of peculiar attributes of PDO cheeses, that are required by specific regulations in order to preserve their typicality and satisfy the consumers.