Proteolytic and Rheological Evaluation of Maturation of Tybo Argentino Cheese

¹ Universidad Nacional de La Plata, Centro de Investigación y Desarrollo, en Criotecnologia de Alimentos, Facultad de Ciencias Exactas, 47 y 116, La Plata (1900), Argentina

Changes in the rheological behavior and viscoelastic properties were analyzed during ripening of a semi-hard cheese (Tybo Argentino) packaged in a plastic film. Casein breakdown was measured by electrophoresis. Degradation of _s1- casein was rapid compared with that of ß-casein. Some rheological parameters obtained from uniaxial compression tests changed during ripening. Hardness decreased, and adhesiveness increased; however, cohesiveness did not change significantly.

An exponential decay equation with two Maxwellian elements and one elastic element in parallel was fitted to characterize stress relaxation curves. Viscoelastic parameters (elastic moduli and relaxation times) were obtained using non-linear regression analysis. The elastic equilibrium modulus and the viscosity of the element with the highest relaxation time decreased during the ripening period.

The rheological parameters were correlated to the formation of water-soluble and TCA-soluble nitrogen and to the concentration of _s1-casein by linear regression equations. Hardness and viscosity had the highest correlation coefficients.

Key Words: cheese • ripening • casein breakdown • rheological properties

Submitted on September 20, 1991
Accepted on July 21, 1992