Use of bacteriocin-producer Lactobacillus sakei for fermented sausages production

The aim of this paper was the technological characterization of a Lactobacillus sakei strain able to produce the bacteriocin sakacin P. Experiments were conducted in vitro, using MRS-based medium, and in vivo, when the strain was inoculated as starter culture in real sausage fermentation

Monitoring of a starter culture for fermented sausages by molecular methods

The ability of a commercial starter culture to perform a sausage fermentation was evaluated by culture -dependent and -independent methods. The starter culture, as well as the sausage during fermentation, was sampled and strains of lactic acid bacteria (LAB) and coagulase negative cocci (CNC) were isolated

Use of bacteriocin-producer Lactobacillus sakei for fermented sausages production

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Use of bacteriocin-producer Lactobacillus sakei for fermented sausages production

The aim of this paper was the technological characterization of a Lactobacillus sakei strain able to produce the bacteriocin sakacin P. Experiments were conducted in vitro, using MRS-based medium, and in vivo, when the strain was inoculated as starter culture in real sausage fermentation.</p

Monitoring of a starter culture for fermented sausages by molecular methods

The ability of a commercial starter culture to perform a sausage fermentation was evaluated by culture -dependent and -independent methods. The starter culture, as well as the sausage during fermentation, was sampled and strains of lactic acid bacteria (LAB) and coagulase negative cocci (CNC) were isolated.</p

Microbiological and Chemical Quality of Minced Meat Packaged in Modified Atmosphere at +1-2°C.

The aim of the work was to determine the shelf-life and the microbiological quality of minced meat packaged in modified atmosphere (MAP, 20% O2, 5% CO2, 75% N2). Changes in the microflora and in the chemical characteristics were monitored for a total period of 10 days. Different samples of minced pork meat and of minced mixed pork and beef meat (50% w/w) were packaged and stored at +1-2°C. The results demonstrated that the minced meat samples studied had a 6 days shelf-life; the microbiological quality, the pH value and the total volatile nitrogen (TVN) were acceptable. After the sixth day, both minced meats started to brown, becoming unacceptable by the consumers.</p

Study of the Ecology of Fresh Sausages and Characterization of Populations of Lactic Acid Bacteria by Molecular Methods

In this study, a polyphasic approach was used to study the ecology of fresh sausages and to characterize populations of lactic acid bacteria (LAB). The microbial profile of fresh sausages was monitored from the production day to the 10th day of storage at 4°C. Samples were collected on days 0, 3, 6, and 10, and culture-dependent and -independent methods of detection and identification were applied. Traditional plating and isolation of LAB strains, which were subsequently identified by molecular methods, and the application of PCR-denaturing gradient gel electrophoresis (DGGE) to DNA and RNA extracted directly from the fresh sausage samples allowed the study in detail of the changes in the bacterial and yeast populations during storage. Brochothrix thermosphacta and Lactobacillus sakei were the main populations present. In particular, B. thermosphacta was present throughout the process, as determined by both DNA and RNA analysis. Other bacterial species, mainly Staphylococcus xylosus, Leuconostoc mesenteroides, and L. curvatus, were detected by DGGE. Moreover, an uncultured bacterium and an uncultured Staphylococcus sp. were present, too. LAB strains isolated at day 0 were identified as Lactococcus lactis subsp. lactis, L. casei, and Enterococcus casseliflavus, and on day 3 a strain of Leuconostoc mesenteroides was identified. The remaining strains isolated belonged to L. sakei. Concerning the yeast ecology, only Debaryomyces hansenii was established in the fresh sausages. Capronia mansonii was initially present, but it was not detected after the first 3 days. At last, L. sakei isolates were characterized by randomly amplified polymorphic DNA PCR and repetitive DNA element PCR. The results obtained underlined how different populations took over at different steps of the process. This is believed to be the result of the selection of the particular population, possibly due to the low storage temperature employed

Culture-Dependent and -Independent Methods To Investigate the Microbial Ecology of Italian Fermented Sausages

In this study, the microbial ecology of three naturally fermented sausages produced in northeast Italy was studied by culture-dependent and -independent methods. By plating analysis, the predominance of lactic acid bacteria populations was pointed out, as well as the importance of coagulase-negative cocci. Also in the case of one fermentation, the fecal enterocci reached significant counts, highlighting their contribution to the particular transformation process. Yeast counts were higher than the detection limit (>100 CFU/g) in only one fermented sausage. Analysis of the denaturing gradient gel electrophoresis (DGGE) patterns and sequencing of the bands allowed profiling of the microbial populations present in the sausages during fermentation. The bacterial ecology was mainly characterized by the stable presence of Lactobacillus curvatus and Lactobacillus sakei, but Lactobacillus paracasei was also repeatedly detected. An important piece of evidence was the presence of Lactococcus garvieae, which clearly contributed in two fermentations. Several species of Staphylococcus were also detected. Regarding other bacterial groups, Bacillus sp., Ruminococcus sp., and Macrococcus caseolyticus were also identified at the beginning of the transformations. In addition, yeast species belonging to Debaryomyces hansenii, several Candida species, and Willopsis saturnus were observed in the DGGE gels. Finally, cluster analysis of the bacterial and yeast DGGE profiles highlighted the uniqueness of the fermentation processes studied