Impact of Milk Thermization on the Quality Characteristics of P.D.O. Canestrato Pugliese Ovine Hard Cheese

The use of raw milk is compulsory in the manufacturing process of most of the European protected designation of origin (PDO) cheeses but, for ovine products, it is often responsible for faulty productions. Since pasteurization is hardly compatible with the PDO concept, a milder treatment (thermization) is allowed in some cases. An investigation was undertaken to assess the effect of thermization on the overall quality of Canestrato Pugliese, a PDO ovine hard cheese of Southern Italy that can be manufactured exclusively from raw milk. Three types of cheese were produced using raw, mild-thermized and high-thermized milk inoculated with a thermophilic commercial starter. The results demonstrated that the heat treatment did not cause remarkable differences in the gross composition, but the microbiological profiles had some differences despite the use of the selected starter. The raw milk cheese contained higher levels (0.5-1 log units) of mesophilic lactobacilli, total viables, total coliforms and enterococci with respect to the thermized counterparts, with the high-thermized cheese showing the lowest levels; these microbiological differences fitted well with the higher content and the different High Performance Liquid Chromatography (HPLC) pattern of soluble nitrogen. The sensory analysis revealed that the thermized cheeses lost some typical sensory characteristics, probably as a consequence of the reduced indigenous microbiota populations. It was concluded that milk thermization could be applied to Canestrato Pugliese manufacturing only together with the development and use of an autochthonous starter.

Automated summary

The use of raw milk is mandatory for most European protected designation of origin (PDO) cheeses, but it often leads to poor production for ovine products. To overcome this issue, a milder treatment called thermization is allowed. A study was conducted to evaluate the effect of thermization on the overall quality of Canestrato Pugliese, a PDO ovine hard cheese from Southern Italy. The results showed that thermization did not significantly alter the composition of the cheese, but there were differences in microbiological profiles and sensory characteristics compared to raw milk cheese. It was concluded that thermization could be applied to Canestrato Pugliese production with the use of an autochthonous starter.