Greek Feta cheese was prepared using as adjunct starter cultures
Enterococcus faecium FAIR-E 198,
E. faecium FAIR-E 243, and their combination. Numbers of enterococci in the control and in the ...batches containing
E. faecium strains as adjunct starters rapidly increased until day 15 of ripening, and then remained constant. Both
E. faecium strains positively affected the counts of non-starter lactic acid bacteria (NSLAB), micrococci and coliforms, while thermophilic cocci were not influenced. Moreover,
E. faecium FAIR-E 243 enhanced the growth of mesophilic cocci and thermophilic bacilli. Physicochemical characteristics, such as pH, moisture, ash, salt in moisture and fat in dry matter (FDM) were not influenced by the addition of the
E. faecium strains. The most pronounced effect was observed in the case of proteolysis. Both
E. faecium strains, either as sole adjunct starter or in combination, increased the proteolytic index and the free amino groups concentration, and enhanced degradation of α
s1- and β-caseins in comparison to the control. Furthermore, the reverse-phase (RP)-HPLC peptide profiles of the water-soluble nitrogen (WSN) fractions were significantly affected by the addition of enterococci. The main volatile compounds produced were ethanol, acetate, acetone, acetaldehyde, acetoin and diacetyl, with highest amounts determined for ethanol, followed by acetate. Both
E. faecium strains positively affected taste, aroma, colour and structure of the full-ripened cheeses, as well as the overall sensory profile. The present work emphasizes the technological significance of
E. faecium strains and supports their use as adjunct cultures in the manufacture of Feta cheese.
In three different dairies (A, B and C) located in Peloponess region (Southern Greece), traditional Feta cheese trials took place February to March using mixtures of sheep's and goat's milk. Only ...small variations in the evolution of microbial groups were observed during the whole ripening period. The main groups, such as thermophilic cocci, mesophilic lactococci, thermophilic lactobacilli, nonstarter lactic acid bacteria (NSLAB), presumptive
Leuconostoc, enterococci and micrococci, reached their highest levels during the first 16 days, and then declined approximately 1–2 log units until the end of ripening. The remaining groups investigated, comprising yeasts, coliforms and
Escherichia coli, were highest at day 4. The yeasts remained constant, while coliforms and
E. coli decreased sharply and were not detectable after 120 days of ripening. A number of 146 isolates (dairy A) taken from all stages of the manufacturing and ripening process were purified and studied.
Lactobacillus plantarum (58/146) and isolates of related species
Lactobacillus pentosus and
Lactobacillus paraplantarum (16/146) were the most common microorganisms found during cheese ripening.
Streptococcus thermophilus (23/146) and
Lactobacillus delbrueckii subsp.
bulgaricus (20/146) were detected in high levels up to 20 days, and then gradually reduced.
Enterococcus faecium (29/146) was found in all manufacturing and ripening stages.
Bacteriocin production by
Enterococcus faecium FAIR-E 198, isolated from Greek Feta cheese, was studied in batch fermentations, under conditions simulating Feta cheese preparation. Maximum enterocin ...activity and growth rate was obtained in de Man–Rogosa–Sharpe (MRS) broth at 37 °C with controlled pH 6.5. The enterocin was produced throughout the growth phase of the microorganism, showing primary metabolite kinetics with a peak activity during the mid-exponential phase. The use of skimmed milk as substrate revealed low enterocin activity. When fermentations were performed in skimmed milk in the presence of rennet, CaCl
2, and a mixed starter culture, no enterocin activity was observed, although the examined strain grew well under the above conditions. Finally, when
E. faecium FAIR-E 198 was applied as adjunct starter in Feta cheese making, no enterocin activity was detected throughout ripening. Results obtained underline the frequently underestimated finding that in vitro production by novel bacteriocinogenic starter or co-cultures is no guarantee for in situ efficiency. It was concluded that the complex food environment thoroughly interferes with bacteriocin production levels.
A total of 129
E. faecium,
E. faecalis and
E. durans strains of food, veterinary and human origin were screened for biochemical properties relevant to their technological performance. Strains ...exhibited low milk acidifying ability and low extracellular proteolytic activity, with food origin and
E. faecalis strains being generally more active. Their peptidase activities were low and mainly specific against glycine-proline- and glutamate-4-nitroanilide, while only food origin and
E. durans strains showed broader substrate specificity. In contrast, their lipolytic activities were relatively higher; food and veterinary origin and
E. faecalis strains were the most lipolytic. The post-electrophoretic detection of esterase activities showed that the esterolytic system of enterococci was rather complex. All species showed strain-to-strain variation in their ability to metabolise citrate and pyruvate, with
E. faecalis strains being generally more active. The main volatile compounds produced in milk were acetaldehyde, ethanol and acetoin; generally,
E. faecalis strains produced the highest concentrations. None of the strains decarboxylated histidine, lysine and ornithine, but the majority produced tyramine from tyrosine, independently of origin and species. In respect of most biochemical properties considered in this study,
E. faecalis strains were generally more active compared to
E. faecium and
E. durans. This was also the case for the isolates of food origin compared to those of veterinary and human origin. Results obtained allow the selection of enterococci strains to be used as adjunct starters in food fermentations. However, a final selection should take into account the potential virulence factors of enterococci.
Citrate metabolism by
Enterococcus faecium FAIR-E 198, isolated from Greek Feta cheese, was studied in various growth media containing citrate either in the presence of glucose, or as the sole carbon ...source, both under aerobic and anaerobic conditions. In de Man–Rogosa–Sharpe (MRS) broth with increasing citrate concentrations, cometabolism of citrate and glucose took place. Glucose was stoichiometrically converted into lactate, while citrate into acetate. Glucose consumption and biomass yield were enhanced with increasing initial citrate concentrations, even though maximum specific growth rate was not. When citrate was used as the sole carbon source in increasing initial concentrations, the main end product was acetate. Small amounts of lactate, formate, ethanol, and acetoin were also produced. In all cases, no significant differences were observed between aerobic and anaerobic conditions. However, when citrate was used as sole carbon source, formate production was favored in the absence of oxygen. The present work shows that
E. faecium is able to utilize citrate in synthetic media, either in the presence of glucose or as the sole carbon source, resulting in energy production and the formation of aroma compounds.
With the ever growing number of products that are targeted at solving a particular problem, rather than addressing all the requirements, which might otherwise be met with a multipurpose product, that ...need to be integrated in an enterprise business workflow, it is critical that data is able to easily flow from one application to another, in order to securely integrate a set of enterprise computer applications. Automation in Business to-Business (B2B) Enterprise Application Integration (EAI) scenarios confronts challenges related to the resolution of data heterogeneities, service discovery and process composition that should be integrated under a secure framework. In this paper, we propose the Secure Enterprise Interoperability Ontology (SENIO) that provides a secure, shared, common understanding of data, services and processes within B2B integration scenarios. SENIO is based on security-related ontologies that are designed to describe security properties of web services, which can be specific, by stating the particular standards/protocols supported, or more general, such as the security mechanisms used and the credentials required. The security properties associated with registered web services as well as requests for web services are security requirements and capabilities. Finally, we present the utilization of SENIO in a real-world B2B scenario, which describes a network of Small and Medium Enterprises (SMEs) cooperating with each other in order to provide secure human resource services.
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