Eureka! Institutional Repository

The subject of this work was the ripening and the study of the physicochemical and rheological properties of the cheeses Ladotyri (PDO) and Graviera of Mytilene. The cheeses were manufactured in Agra of Mytilene at the Tastani’s creamery and matured for 6 months in Thessaloniki packed under vacuum at 16oC. The analyzes were carried out at the laboratories of the Food Technology Department of ATEI of Thessaloniki. Both physicochemical and rheological tests were performed in duplicate for each cheese sample monthly. Compositional parameters such as protein with the Kjeldahl method, fat with Gerber method, pH, humidity, etc. were determined. The study of rheological characteristics was carried out by the method of texture profile analysis (TPA) and the stress-relaxation test. Both tests were conducted with the TA-XT Plus Universal Texture Analyzer. Through TPA test, rheological properties of the cheeses were determined such as hardness, brittleness, cohesiveness, etc., while the stress relaxation method determined the ratio of the residual relaxation force to the initial relaxation force, which expresses elasticity. The results showed that the chemical composition, especially the moisture and protein, directly affected the rheological properties of the cheeses. In particular, it was observed that Graviera, because of its lower moisture content in relation to Ladotyri, is richer in protein but also in fat, resulting in higher values in rheological properties. That is, the denser protein matrix of Graviera is responsible for its more cohesive and harder texture. Also, during the first three months of ripening, the moisture decreased in both cheeses, resulting in an increase in all rheological properties. In contrast, during the last three months of ripening, all the rheological properties of the cheeses have decreased, due to proteolysis and, consequently, weakening of their protein matrix.