Characterisation of a soft cheese proteolysis by RP-HPLC analysis of its nitrogenous fractions. Effect of ripening time and sampling zone

VERDINI, RA; ZORRILLA, SE; RUBIOLO, AC

INTERNATIONAL DAIRY JOURNAL

Elsevier

Año: 2004 vol. 14 p. 445 - 454

0958-6946

Port Salut Argentino cheeses were studied considering different ripening times (1, 6, 13, 27, and 56 days) and two sampling zones (central and external). Moisture content, salt concentration, water-insoluble fraction, water-soluble fraction, and free amino acids in the sulfosalicylic acid-soluble fraction were analysed. Moisture and salt contents at the beginning of the ripening were higher in external zone than in central zone (51 and 46% w/w moisture, 0.95 and 0.25% w/w NaCl, respectively). Cheeses reached uniform salt content but not uniform moisture content during the 56 days of ripening. The hydrolysis of as1-casein during cheese ripening was modelled with a first order kinetics. The kinetics constant of as1-casein degradation was 0.017 day–1. Most of the water-soluble peptides increased during cheese ripening, particularly from 13 days of ripening. Free amino acids content also increased from 13 days of ripening. Amino acids that characterised the ripening of Port Salut Argentino cheese were leucine, lysine, asparagine, phenylalanine, threonine, tyrosine, glutamine, and valine. Proteolysis increased in both zones during ripening and there was no appreciable difference between zones using any of the methods for investigating proteolysis.