Microbiological and chemical characterization of Fiore Sardo, a traditional Sardinian cheese made from ewe's milk

Abstract

The purpose of this study was to assess the chemical and microbial characteristics of 12 batches of artisanal Fiore Sardo, a protected designation of origin (PDO) hard cheese made from raw ewe's milk without addition of starters, during maturation. High standard deviations were observed for moisture percentage, total solids percentage and NaCl percentage content, possibly owing to differences in manufacturing processes and/or milk composition. Total mesophilic bacteria varied between 10 log10 cfu/g in 48‐h‐old cheese samples and 3 log10 cfu/g in 9‐month‐old samples. Total coliforms and staphylococci showed the highest counts at 48 h of ripening then decreased significantly, dropping to levels below 2 log10 cfu/g at 3 months of maturation. Lactic acid bacteria and enterococci were the dominant micro‐organisms throughout maturation. They were mainly represented by the species Lactococcus lactis ssp. lactis, Enterococcus faecium, Lactobacillus plantarum and Lactobacillus casei group. Low levels of yeasts were detected throughout the maturation period of the cheese. Debaryomyces hansenii and Kluyveromyces lactis var. lactis were the prevalent yeast species isolated.

Effect of different salting technologies on the chemical and microbiological characteristics of PDO Pecorino Siciliano cheese

“…The counts determined on the medium specifically employed for enterococci showed that they were less concentrated, of about two log cycles, than other LAB. Our data almost agreed with those observed for different ripened raw ewes' milk cheeses analysed approximately at the same period of ageing [39], even though higher levels were reported for Pecorino Siciliano cheese investigated at 3-month ripening [48]. Enterococci have also been detected at higher levels than ours at 12-month ripening for some Pecorino-type cheeses [14].…”

“…This trend was observed in other similar Italian cheeses [4] and the concentration levels of rod LAB was, on average, in the same order of magnitude of those reported by other authors [25,39]. In a previous work carried out on the microbial ecology of Pecorino Siciliano cheese produced in winter and spring [48], data, collected at latest at 90 days of ripening, showed that mesophilic rod and coccus LAB were approximately at the same level (about 10 7 cfu/g).…”

“…PCS and butyric clostridia were not found in any sample. With the exception of yeasts, whose levels were in the range of those known for similar aged products [16,39], but lower than those previously reported for Pecorino Siciliano ripened for 3 months [48], the other microbial populations (TPC, Enterobacteriaceae and pseudomonads) were detected at relatively high levels. In fact, in comparison with other raw ewes' milk cheeses, our data showed higher levels of the unwanted bacteria, especially Enterobacteriaceae.…”

“…Except streptococci, all LAB found in this study are generally reported to be associated with Italian raw ewes' milk cheeses [8,14,39,49].…”

“…The species C. freundii, Enterobacter spp., Es. coli and K. oxytoca have been already reported for this type of cheese, but not after the first month of ripening [39]. Also Serratia genus was isolated during the ripening of Italian Pecorino cheeses [7].…”