Influenza del contenuto in cellule somatiche del latte ovino sulle caratteristiche sensoriali di formaggio Pecorino /Influence of ewe milk somatic cell count on the sensory characteristics of Pecorino cheese

Introduction - Ewe milk somatic cell count can influence some cheesemaking parameters as well as the final characteristics of the cheese. In particular, a high SCC determines a reduced response to the action of the rennet with an increased curd formation rate and a decreased clot firmness thus causing, overall, a higher moisture content in the cheese. Casein hydrolysis determines cheese texture changes and lipases increase the degree of lipolysis, especially during storage, resulting in decreased fat content, and increased volatile fatty acids content as well as in possible repercussions on the organoleptic characteristics of the product. Aim - The aim of this study was to evaluate the effect of a different number of somatic cells (Somatic Cell Count - SCC) on some sensory characteristics of Pecorino cheese ripened for 60 days. Materials and methods - For this purpose cheeses were made starting from milk with low SCC (<500.000 cells/ml), medium SCC (1.000.000-1.500.000 cells/ml) and high SCC (>2.000.000 cells/ml). The cheeses were subjected to chemical- physical (pH), composition (moisture, protein, fat and ash) and sensory analyses (electronic nose, duo-trio and ranking test and sensory profile).Results and discussion - The average pH value of cheeses obtained from milk with a high SCC is significantly higher (5.37) than that obtained from milk with average (5.23) (P<0.05) or low SCC (5.15) (P<0.01). The chemical composition showed a higher moisture content in cheese obtained from milk with high SCC (42.91%) compared to that obtained from milk with low SCC (42.03%) (P<0.01). No difference was found for the values relating to electronic nose signals, while the other sensory analyses showed that the cheeses made with high SCC milk differ from the other two types, in particular for hardness and graininess. Conclusions - The findings in this work confirmed that the sensory characteristics of cheese may be affected by the somatic cells count of the milk used. However, the 60 day ageing period used in our experiment did not determine changes in the flavour which, according to some authors, would only change significantly with a longer ripening time. Nonetheless this period was sufficient to determine texture alterations that negatively affected the taste of cheeses made from milk with high SCC.