Effect of ripening temperature and sampling site on the proteolysis of Reggianito Argentino cheese

SIHUFE G. A.; ZORRILLA S. E.; RUBIOLO A. C.

Viña del Mar (Chile)

Congreso; 10th International Congress on Engineering and Food; 2008

Instituto Chileno para la Ingenieria de Alimentos

Proteolysis is the most complex and important event that occurs during ripening of a great number of cheese varieties and contributes to the development of characteristic flavour and texture. During proteolysis, part of the caseins is converted into water-soluble nitrogenous compounds, such as peptides and amino acids. The activity of enzymes during proteolysis varies due to medium conditions, such as salt content and temperature. The objective of this study was to evaluate the effect of ripening temperature elevation and sampling site on the proteolysis of Reggianito Argentino cheese. Cheeses ripened at 12 °C or 18 °C and 85% relative humidity were assayed at 62, 123 and 186 days of ripening at 2 different sampling zones (central and external). Proteolysis was evaluated by determination of maturation index, electrophoresis in polyacrilamide gel (PAGE) and chromatography (RP-HPLC) of peptides and aminoacids. Seven fractions were identified by PAGE: g-casein, b-casein, as1-casein, as1-I-casein and 3 unknown fractions possibly related to as1-casein degradation. Thirty-six chromatographic peaks were determined by RP-HPLC. The amino acids present in higher concentrations were Glu, His, Val, Leu y Lys, which showed values higher than 50 mg/100 g cheese in cheeses ripened at 12 °C. The information obtained was successfully summarised in 3 dimensions accounting for more than 70% of the data variation using Principal Component Analysis. The source of variation explained by PC1 (45.5% VAR) can be related to the ripening time due to the scattering of samples clearly increases as ripening time increases. The source of variation explained by PC2 (17.4% VAR) and PC3 (8.6% VAR) could be related to sampling zone and ripening temperature, respectively. The PC loadings plot showed interesting groupings that allowed identifying which variables were strongly influenced by the treatments studied. These studies will allow establishing precisely an optimum ripening time when a higher storage temperature is used rather than the traditional temperature, and to improve the understanding of one of the main events that occurs during the ripening of a traditional Argentinean hard cheese.