Effect of storage time on microstructure, viscoelastic and biochemical parameters of Afuega'l Pitu cheese (PDO): Atroncau Blancu and Roxu varieties

Structural (cryo-scanning electron microscopy), and viscoelastic changes (dynamic rheometry), with storage time in Afuega'l Pitu cheese Blancu (B) and Roxu (R) varieties were observed. Biochemical parameters were also measured. pH, fat, and protein content did not change during the storage time for B and R varieties. R micrographs showed large fused-fat particles within the protein matrix, as a consequence of a specific kneading step to mix the partially dehydrated curd with paprika and salt. B samples exhibited more homogeneous microstructures with small fat globules, improving viscoelastic parameters such as conformational stability (stress amplitude, sigma(max)) and network flexibility (strain amplitude, gamma(max)). The longer storage time, the higher total solids (TS) content (lower moisture to protein ratio-MPR) for B and R varieties, evolving into a less porous microstructure, which increased the thickening of the protein strands. These structural changes were shown in the enhanced rigidity (high complex modulus, G*), structural stability (high sigma(max)) and more shear-sensitive or physically structured (lower gamma(max)) cheese network.