Pecorino Crotonese cheese: study of bacterial population and flavour compounds

The diversity and dynamics of the dominant bacterial population during the manufacture and the ripeningof two artisanal Pecorino Crotonese cheeses, provided by different farms, were investigated by thecombination of culture-dependent and -independent approaches. Three hundred and thirty-three strainswere isolated from selective culture media, clustered using Restriction Fragment Length Polymorphismand were identified by 16S rRNA gene sequencing. The results indicate a decrease in biodiversity duringripening, revealing the presence of Lactococcus lactis and Streptococcus thermophilus species in the curdand in aged cheese samples and the occurrence of several lactobacilli throughout cheese ripening, with thedominance of Lactobacillus rhamnosus species. Bacterial dynamics determined by Denaturant Gradient GelElectrophoresis provided a more precise description of the distribution of bacteria, highlighting differencesin the bacterial community among cheese samples, and allowed to detect Lactobacillus plantarum, Lactobacillusbuchneri and Leuconostoc mesenteroides species, which were not isolated. Moreover, the concentrationof flavour compounds produced throughout cheese ripening was investigated and related to lacticacid bacteria presence. Fifty-seven compoundswere identified in the volatile fraction of Pecorino Crotonesecheeses by Gas ChromatographyeMass Spectrometry. Esters, alcohols and free fatty acids were the mostabundant compounds, while aldehydes and hydrocarbons were present at low levels.