Evaluation of Serpa cheese proteolysis by nitrogen content and capillary zone electrophoresis

Abstract

Proteolysis of Serpa cheese produced traditionally (B) and semi‐industrially (C) was evaluated for the first time by determination of nitrogen content and capillary zone electrophoresis (CZE). A citrate dispersion of cheese was fractionated to determine the nitrogen in pH 4.4, trichloroacetic and phosphotungstic acid soluble fractions (pH 4.4‐SN, TCA‐SN and PTA‐SN, respectively). The pH 4.4‐SN was significantly higher for B ( P < 0.001), while TCA‐SN was significantly higher for C ( P < 0.001). PTA‐SN was also higher for C but at 60 days ripening no significant difference was found between B and C. Degradation of α s1 ‐ and β‐caseins evaluated by CZE was in good agreement with the maturation index (pH 4.4‐SN/TN).