Study of ripening on Castelmagno PDO cheese produced in Piedmont mountains

Study of ripening on Castelmagno PDO cheese produced in Piedmont mountains M. Bertolino*, M. Giordano, L. Rolle and G. Zeppa Turin University, Department of Exploitation and Protection of the Agricultural and Forestry Resources, Italy marta.bertolino@unito.it Castelmagno is a semi-hard cheese produced in mountains of Cuneo Province (Piedmont-Italy), made from raw milk without the use of starter. After cutting, the curd is left 24 hours at room temperature and then putted under acidified whey for 3 days. Then, the curd is crumbled, salted, putted into cylindrical moulds and pressed strongly. Finally the cheese is ripened in natural caves for at list 2 months. The commercial product has a cylindrical shape (20 cm high, 20-23 cm in diameter) and a weight comprised between 4-6 Kg. Although Castelmagno PDO cheese plays an important role in Piedmont dairy economy, there is a lack of knowledge on its evolution during the ripening. Therefore the aim of this work was to define its glycolysis, proteolysis, lipolysis and structural evolution during the ripening of 3 batches of Castelmagno PDO cheese. The analyses were assessed at 1, 30, 60, 90 and 150 days of ripening by HPLC analysis of sugars, by urea-PAGE of the pH 4.6-insoluble fractions, by SPME-GC-MS of volatile compounds and by Texture-Analysis for the textural characterisation. Concerning the HPLC analysis on sugars already at the first day of ripening all of them were metabolised into lactate. During the ripening is possible to observe a diminution of lactate concentration due to its metabolization into butyrate and acetate that shown an increase. Regarding the degradation of citrate it was possible to observe an increase of diacetyl concentration as its secondary metabolites. In relation to proteolysis all cheeses showed a higher degradation of s1-casein compared to -casein. With reference to the lipolysis during the ripening the principal chemical classes derived from the pathways of the free fatty acids (esters, lactones, aldheydes, alcohols) showed the same trend. Their concentration increased from the first to the thirtieth day of ripening. After their concentration decreased until the ninetieth day and then increased until the end of the ripening. Concerning the texture it was possible to observe that values of hardness, adhesiveness, gumminess and chewiness parameters increased during ripening in particular after the ninetieth day. Keywords: Castelmagno PDO cheese, glycolysis, proteolysis, lipolysis, ripening