Effects of the freezing process on the proteolysis during the ripening of Port Salut Argentino cheese

VERDINI, RA; ZORRILLA, SE; RUBIOLO, AC

INTERNATIONAL DAIRY JOURNAL

Elsevier

Año: 2005 vol. 15 p. 363 - 370

0958-6946

Effect of the freezing process (freezing at -30°C, frozen storage at -22°C for 30 days and thawing at 5°C) on the proteolysis during the ripening of Port Salut Argentino cheese was studied. Cheeses were sampled at different ripening times (1, 6, 13, 27 and 56 days) and two sampling zones (central and external). Moisture content, salt concentration and RP-HPLC of the nitrogenous fractions (water-insoluble fraction, water-soluble fraction and free amino acids in the sulfosalicylic acid-soluble fraction) were analysed.  The freezing process did not affect moisture and salt contents at the beginning of the ripening nor moisture and salt redistribution during the studied ripening period. However, the freezing process affected several stages of the biochemical pathways of proteolysis during the ripening of Port Salut Argentino cheeses frozen prior to ripening. There was increasing hydrolysis of as1-casein and as1-I-casein, which might be related to conformational changes in as1-casein affecting its susceptibility to chymosin attack. Moreover, there was an increasing hydrolysis of peptides of the water-soluble fraction (including as1-CN (f1-23)) along with an early development of free amino acids, which might be related to increasing levels of enzymes released by microorganisms damaged by the freezing process.