UNI-MB - logo
UMNIK - logo
 
BF, Oddelek za zootehniko, Ljubljana (BFZOO)
  • Microbial stability and safety of traditional Greek Graviera cheese : characterization of the lactic acid bacterial flora and culture-independent detection of bacteriocin genes in the ripened cheeses and their microbial consortia
    Samelis, John ...
    The microflora of four batches of traditional Greek Graviera cheese was studied at 5 weeks of ripening, and 200 lactic acid bacteria (LAB) isolates were phenotypical characterized and screened for ... antilisterial bacteriocins. The cheese were also analyzed for organic acids by high-performance liquid chromatography and for the potential presence of 25 known LAB bacteriocin genes directly in cheese and their microbial consortia by PCR. All batches were safe according to the European Union regulatory criteria for Listeria monocytogenes, Salmonella, enterobacteria, and coagulase-positive staphylococci. The cheese flora was dominanted by nonstarter Lactobacillus casei/paracasei (67.5%) and Lactobacillus plantarum (16.3%) strains, whereas few Streptococcus thermophilus (3.8%), Lactococcus lactis subsp. lactis (0.6%), and Leuconostoc (1.9%) organisms were present. Enterococcus faecium (9.4%) and Enterococcus durans (0.6%) were isolated among the dominant LAB from two batches; however, enterococci were present in all batches at 10- to 100-fold lower populations than mesophilic lactobacilli. Sixteen E. faecium isolates produced antilisterial anterocins. In accordance, enterocin B gene was detectable in all cheeses and enterocin Pgene was present in one cheese, whereas the consortia of all cheeses contained at least two of the enterocin A, B, P, 31, L50A, and L50B genes. Plantaricin A gene also aplified from all cheeses. Mean concentrations of lactic, acetic, citric, and propionic acids in the ripened cheeses exceeded 1.5% in total, of which approximately 0.9% was lactate. Thus, organic acid contents constitute important hurdle factor for inhibiting growth of pathogens in traditional Graviera chees products, with LAB bacteriocins, mainly enterocins, potentially contributing to increased cheese safety.
    Vir: Journal of food protection. - ISSN 0362-028X (Vol. 73, no. 7, 2010, str. 1294-1303)
    Vrsta gradiva - članek, sestavni del
    Leto - 2010
    Jezik - angleški
    COBISS.SI-ID - 2697096

vir: Journal of food protection. - ISSN 0362-028X (Vol. 73, no. 7, 2010, str. 1294-1303)

loading ...
loading ...
loading ...