Microbial identification and evaluation of their dynamic distribution during the ripening of a naturally fermented ham in Taiwan
Date Issued
2009
Date
2009
Author(s)
Seng, Lock Ying
Abstract
Isolation and identification of the autochthonous starter from a naturally fermented meat allows control of the fermentation process and promises microbiological safety for this specialty. Thus the purpose of this study was to identify the lactic acid bacteria and coagulase-negative cocci present in a traditional Taiwanese naturally fermented ham (TNFH) and to study the microbial dynamics at different ripening stages; the approach was a combination of conventional microbiological cultivation, polymerase chain reaction-denaturing gradient gel electrophoresis and DNA sequencing. The characteristics of each isolated strains were also investigated. In total, twelve different strains of lactic acid bacteria and three Staphylococcus strains were identified in the TNFH samples. The bacterial ecology on the surface of the samples was mainly characterized by the stable presence of Lactobacillus sakei and Staphylococcus saprophyticus; nonetheless Leuconostoc mesenteroides and Carnobacterium divergens were the most abundant bacteria found in the final product. In addition, Microbacterium spp., Carnobacterium spp., Enterobacter spp., Brochothrix spp., Enterococcus spp., and Bacillus spp. were also present at the beginning of the ripening, but few bacteria were found at the center of the TNFH samples during the early ripening stages. However, after 30 days of ripening, the microbial ecology at the center of the TNFH samples paralleled that of the surface. Results of characterization of each strains isolated from TNFH indicated that Lc. lactis subsp. lactis, Lb. sakei, Lc. lactis subsp. cremoris and Staph. xylosus may use as starter cultures for manufacturing fermented meat.ur findings showed that the naturally fermented ham in Taiwan demonstrated a very different ecology when comparing with other fermented meat products. This study also confirmed that combination of cultivation, PCR-DGGE and DNA sequencing can be used to effectively describe the microbial communities of Taiwanese naturally fermented ham. This information could help us to design autochthonous starter cultures.
Subjects
fermented ham, denaturing gradient gel electrophoresis, flora distribution
Type
thesis
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