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New strains are desirable to diversify flavour of fermented dairy products. The objective of this study was to evaluate the potential of Leuconostoc spp. and Lactobacillus spp. in the production of aroma compounds by metabolic fingerprints of volatiles. Eighteen strains, including five Lactobacillus species (Lactobacillus fermentum, Lactobacillus helveticus, Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus sakei) and three Leuconostoc species (Leuconostoc citreum, Leuconostoc lactis, and Leuconostoc mesenteroides) were incubated for 5 weeks in a curd-based slurry medium under conditions mimicking cheese ripening. Populations were enumerated and volatile compounds were analysed by headspace trap gas chromatography-mass spectrometry (GC-MS). A metabolomics approach followed by multivariate statistical analysis was applied for data processing and analysis. In total, 12 alcohols, 10 aldehydes, 7 esters, 11 ketones, 5 acids and 2 sulphur compounds were identified. Very large differences in concentration of volatile compounds between the highest producing strains and the control medium were observed in particular for diacetyl, 2-butanol, ethyl acetate, 3-methylbutanol, 3-methylbutanoic acid and 2-methylbutanoic acid. Some of the characterized strains demonstrated an interesting aromatizing potential to be used as adjunct culture.

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-Karakačanski skakutanac is an artisanal fresh sheep cheese produced on a small scale in a limited area of eastern Croatia. It is manufactured from unrefrigerated raw sheep milk immediately after milking, without the addition of starter culture, and coagulated with industrial rennet. To date, no microbiological or molecular characterization of the biodiversity of the microbiota has been performed. The objective of this study was to obtain an initial insight into the biodiversity of the microbial community associated with this cheese during the production season and shelf life period. Eleven cheeses were obtained from a dairy farm at 14-day intervals during the lactation period of east Friesian sheep in 2007. Bacterial DNA was isolated directly from cheese on the first, second and third day of the cheese shelf life, resulting in a total of 33 DNA samples. Extracted DNA was used as a template for PCR-ARDRA and PCR-DGGE analysis. The use of dual culture-independent approaches revealed similar results and indicated predominance of Lactococcus lactis.

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