Microbial characterization of an artisanal production of Robiola di Roccaverano cheese

摘要

Robiola di Roccaverano, from the Piedmont region ofItaly, is a Protected Designation of Origin soft cheesemade with raw goat milk. The peculiarity of this cheeseis that during the manufacturing process, a naturalstarter culture (NC) is added to raw milk. This studyexamined the viable microorganisms of technologicalinterest, including lactic acid bacteria and fungalpopulations, in samples of raw milk, NC, and fresh andripened cheese collected from one dairy using culturedependenttechniques. First, the isolated colonies wereanalyzed using random amplification of polymorphicDNA (RAPD) PCR, and strains with similar fingerprintswere clustered together. Further, representativeisolates of each group were subjected to 16S or 26S ribosomalDNA sequencing. Finally, species-specific PCRwas conducted to distinguish the Lactococcus lactis ssp.lactis and Lc. lactis ssp. cremoris. Among the studiedlactic acid bacteria, 13 RAPD profiles were obtained,corresponding to 9 different bacterial species or subspecies.Concerning mold and yeast isolates, 5 species werefound that coincided with 5 RAPD types. Observingthe strains isolated in the study, Lc. lactis was the mostprevalent species in raw milk and NC samples, andLeuconostoc mesenteroides was the predominant speciesidentified in 5- and 15-d cheese isolates. Furthermore,whereas only these 2 species were detected in NC, Enterococcusand Lactobacillus genera were found in rawmilk and cheese, respectively. Concerning the mold andyeast isolates, in NC Kluyveromyces spp. was mainlyfound, and in cheese samples the representative specieswere Geotrichum candidum and Yarrowia lipolytica.Finally, raw milk and cheese safety were evaluated, andthe samples complied with the standard required byEuropean Commission regulation number 2073/2005.