Microbial evolution of traditional mountain cheese and characterization of early fermentation cocci for selection of autochtonous dairy starter strains

• The microbial evolution and composition of Mountain cheese was investigated.
• Lactococci, streptococci and enterococci were the dominant genera.
• Lactococci and streptococci were investigated for starter selection.
• The majority of biotypes produced pleasant olfactory flavours.
• Lactococcus lactis 68 and Streptococcus thermophilus 93 were selected as starter strains.

The microbial population of Traditional Mountain (TM) cheese was investigated and characterized for the selection of cocci suitable for developing new starter cultures. Samples of milk, curd and cheese at different ripening times were enumerated in selective culture media and 640 colonies were isolated from curd and cheese after 24 h of ripening. The Lactic Acid Bacteria (LAB) isolated from M17 were clustered into 231 biotypes by RAPD-PCR analysis and identified as Lactococcus lactis, Streptococcus thermophilus and Enterococcus faecalis. Forty percent of enterococci showed the in vitro ability to inhibit raw milk resident coliforms, but they were excluded as possible starters due to the presence of associated risk factors. All lactococci and streptococci were tested for their technological properties; 4 Lc. lactis subsp. lactis and 2 Sc. thermophilus which were fast acidifiers and did not produce unpleasant flavours were subjected to the freeze-drying stability test. Lc. lactis subsp. lactis biotype 68 and Sc. thermophilus biotype 93 showed the best technological properties and may be appropriate for cheese production. This work gave evidence of the high biodiversity of TM-cheese autochthonous biotypes which could be used as starter cultures for the improvement of TM-cheese technology.