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Biodiversity and characterization of Staphylococcus species isolated from a sma...

The level and the diversity of the staphylococcal community occurring in the environment and dairy products of a small manufacturing dairy plant were investigated. Species identification was performed using different molecular methods, viz. Multiplex-PCR, amplified ribosomal DNA restriction analysis (ARDRA), and sodA gene sequencing. The main species encountered corresponded to Staphylococcus equorum (41 isolat...

Antimicrobial effects of chitosans and chitooligosaccharides, upon Staphylococc...

The objective of this study was to elucidate the controversial relationship between the molecular weight (MW) of chitosans and their antibacterial activity (upon different inoculum levels, at several concentrations). The influence of food components on the activity was also ascertained, as well as acceptance by a sensory panel. All the compounds tested exhibited antibacterial activity against Staphylococcus aur...

Changes in the pool of free fatty acids in ovine, bovine and caprine milk fats,...

Lipolysis catalysed by lipases, native or released by natural microflora in milk, plays a key role in development of aroma and flavour throughout cheese ripening. This research effort was aimed at a deeper understanding of the action of two wild strains used in traditional ewe’s milk cheesemaking in Portugal, viz. Lactococcus lactis and Debaryomyces vanrijiae. They were both tested as viable cells and cellfree ...

Contribution of coagulant and native microflora to the volatile-free fatty acid...

The contributions of the coagulant Cynara cardunculus and of the microflora of raw milk to the volatile-free fatty acid profile of Serra da Estrela cheese were evaluated. The experimental design included both a model system and, dual cheeses. The study in the model system showed that isovaleric acid was the predominant volatile compound after 7 d of ripening. The systems inoculated with Enterococcus faecium pro...

Effect of dairy farm and milk refrigeration on microbiological and microstructu...

This work was aimed at enumerating the viable microorganisms in ripened Serra da Estrela cheeses, manufactured from both refrigerated and non-refrigerated milk, in various dairies located throughout the demarcated region. Scanning electron microscopy was used to analyze the microstructure, and thus aid in understanding possible differences in their microbiological profile. The cheeses were allowed to ripen unde...

Enzymatic activities of non-starter lactic acid bacteria isolated from a tradit...

Four strains of lactic acid bacteria, previously isolated from traditional Serra da Estrela cheese and duly identified as Lactobacillus paracasei ssp. paracasei, Leuconostoc mesenteroides ssp. dextranicum, Lactococcus lactis ssp. lactis and Enterococcus faecium, were tested for their aminotransferase, oxidase and dehydrogenase activities towards five amino acids in free form: two branched-chain (leucine and val...

Amino acid and soluble nitrogen evolution throughout ripening of Serra da Estre...

Four batches of Serra da Estrela cheese originating from as many dairy farms were sampled throughout the ripening period, and assayed for the evolution of free amino acid (FAA) content, total nitrogen content (TN), water-soluble nitrogen content (WSN), trichloroacetic acid-soluble nitrogen content (TCASN) and phosphotungstic acid-soluble nitrogen content (PTASN). The WSN content increased from 1% (on the day of...

Storage and lyophilization effects of extracts of Cynara cardunculus on the deg...

Clotting and proteolytic activities are important parameters when evaluating rennets for cheesemaking. Both these activities were determined for extracts of the plant Cynara cardunculus in fresh form and after lyophilization followed by reconstitution, either in water or in citrate buffer (pH 5.4) and stored for up to 4 weeks at 4°C. The patterns of degradation of ovine and caprine caseins were followed by urea...

Microstructural and microbiological relationships in matured Serra da Estrela c...

Relationships between flavour and microbiological profiles in Serra da Estrela ...

Cheeses manufactured in certi"ed dairies in the Portuguese region of Serra da Estrela, using refrigerated and non-refrigerated raw sheep milk, were quantitatively evaluated in terms of indigenous micro#ora and volatile compounds during a ripening period of up to 6 mo. Viable counts were obtained for lactococci, lactobacilli, leuconostoc, enterococci, yeasts, Enterobacteriaceae and staphylococci; analyses of vol...