Microbiology and biochemistry of Pecorino umbro cheese during ripening

A microbiological and biochemical characterization of Pecorino Umbro cheese during ripening is reported. Analyses were conducted on the under rind and core layers of the cheese from three batch productions. In the 60 day-old ripened cheese there were high numbers of starter lactic acid bacteria but coliforms were not detected. Enterococci and, in particular, non-starter lactic acid bacteria increased throughout ripening. A gradient of salt in moisture persisted from the under rind to the core until about 21 days. During the same period, the formation of pH 4.6 soluble N and 12% TCA-soluble N was slightly greater in the interior region, but from 35 days onwards, hydrolysis markedly increased on the cheese surface. The proteolytic activity (peptidases and proteinase) greatly increased between 28 and 42 days of ripening. A decreasing gradient of the proteolytic activity was noted from the cheese surface to the core. The electrophoresis and Reversed Phase-HPLC analyses showed hydrolysis of the alpha-s1- and beta-caseins and the production of various sized peptides. Esterolytic and lipolytic activities were present from the first stages of ripening giving a final content of free fatty acids which approached one third of those from a long-ripened Pecorino. Some interpretations about the complex dynamics of the Pecorino Umbro cheese ripening are given.