Microbial characteristics of Conciato Romano: an artisanal cheese made from raw sheep’s milk

摘要

The aim of this study was to assess the microbial characteristics of a batch of Conciato Romano during manufacturing and ripening. Conciato Romano is a traditional cheese made from raw sheep’s milk without starter cultures in the province of Caserta (Southern Italy) using traditional methods. A total of 7 samples (raw milk, curd and cheese wheels taken after 25, 60, 120 and 180 days of ripening) were screened for hygiene indicators microorganisms counts (total viable count, Enterobacteriaceae, total coliforms, E. coli , clostridia sulphite reducing, yeasts, coagulasepositive staphylococci, enterococci), for autochthonous lactic acid flora counts (mesophilic and thermophilic lactococci and lattobacilli), and also for Salmonella spp. and Listeria monocytogenes presence. In raw milk, low values were detected for total aerobic flora (3.2 log cfu/mL), Enterobacteriaceae and total coliforms (2 cfu/mL), and the autochthonous starter lactic flora was predominant (3.2 log cfu/mL). During ripening, total aerobic flora was constant (107-108 cfu/g); total coliforms, E. coli, Enterobacteriaceae and yeasts were not detected starting from the 60th day of ripening. Enterococci ranged from 4.2 to 6.2 log cfu/g. The mesophilic lactic flora was dominant with values always >6 log cfu/g during the whole ripening period. Pathogens were never detected. The results of this study highlighted how the raw milk indigenous lactic flora, the traditional production techniques and the cheesemaker’s experience are essential to guarantee the unique nature of Conciato Romano .