Secondary proteolysis of Fynbo cheese salted with NaCl/KCl brine and ripened at various temperatures

Abstract

Effects of temperature and salt substitution on secondary proteolysis of Fynbo cheese were studied and different peaks of the chromatographic profiles were examined. Cheeses, salted in solutions of NaCl (190 g l-1) and NaCl/KCl (100 g l-1/100 g l-1) and ripened at 5, 12, and 16 ºC, were sampled during 90 days at two different zones. Samples were analysed by RP-HPLC of the trichloroacetic acid-soluble fraction. The information was successfully summarized in 2 dimensions, accounting for 86.5% of data variation using principal component analysis. The source of variation explained by PC1 (77.1% VAR) was related to the ripening time. Two groups of chromatographic peaks were distinguished according to the sign of PC2 loading. Total salt concentration and ripening temperature affected secondary proteolysis significantly, while NaCl replacement by KCl had no affect. An important peptide produced during cheese ripening (as1-casein (f1-23)) was tentatively identified, taking into account the chromatographic profile and the amino acid composition of the peak isolated.