Studio della microflora lattica autoctona del Pecorino di Tramonti: un formaggio artigianale prodottonel territorio del Parco Regionale dei Monti Lattari

Abstract

The natural lactic flora of Tramonti Pecorino, a typical cheese manufactured in the “Lattari mountain” area in the province of Salerno (Italy), was investigated. Particular attention was paid to the assessment of the growth dynamics and to the molecular identification of the indigenous lactic acid bacteria involved in the ripening of this cheese made with raw sheep milk without starter cultures. Two batches of cheese were produced for the trial: the first called Classical Tramonti Pecorino (CTP) and the second called chilli Tramonti Pecorino (CTP1). In total, 4 samples from CTP were taken, the first one on the manufacturing day and the others on the 39o, 60o and 94o ripening day. Subsequently, 4 samples from CTP1 were taken, the first one on the manufacturing day and the others on the 30o, 50o and 105° ripening day. Lactobacillus and Lactococcus were enumerated and randomly isolated on MRS and LM17 agar (32oC x 48h ± 2h -mesophilic flora- and 42°C x 48h ± 2h -thermophilic flora) in both batches of pecorino cheese. The gram positive and catalase negative colony (n. 101 in CTP and n. 67 in CTP1) were genotipically identified by Ribotyping. In CTP the thermophilic lactic flora initial values of log10 5.2 cfu/g (Lactobacillus) and log10 7.5 cfu /g (Lactococcus) reached the average values of log10 5.5 cfu/g at the end of ripening. The mesophilic Lactobacillus and Lactococcus showed an initial charge of log10 8.3 cfu /g reaching, at the end of ripening, the values of log10 5.3 and 6.5 cfu / g. In CTP1, mesophilic Lactobacillus attested on 107 cfu/g during whole ripening time while thermophilic Lactobacillus, at the end of ripening reached 106 cfu/g from initial values of 105 cfu/g; on average, mesophilic and thermophilic Lactococcus attested on 106 cfu/g from the beginning of ripening.Ribotyping allowed us to detect 4 lactic acid bacteria species in both baches: Enterococcus faecium (69,30% in CTP; 64,17% in CTP1), Lactococcus lactis spp. cremoris (18,81% in CTP; 25,37% in CTP1), Enterococcus faecalis (8,91% in CTP; 5,97% in CTP1), Enterococcus durans (2,97 % in CTP; 4,47% in CTP1). The four species of lactic bacteria identified by Ribotyping show the diversity of indigenous lactic acid bacteria that characterizes both Tramonti Pecorino cheese examinated.