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- Production of antilisterial bacteriocin by Pediococcus acidilactici HA‑6111‑2 under different stress conditionsPublication . Engelhardt, Tekla; Albano, Helena; Kiskó, Gabriella; Mohácsi-Farkas, Csilla; Teixeira, Paula
- Evaluation of a bacteriocinogenic Lactobacillus plantarum strain on the microbiological characteristics of “Alheira de Vitela”Publication . Macieira, Ariana; Albano, Helena; Pinto, Miguel; Linheiro, Raquel; Barbosa, Joana; Teixeira, PaulaLactic Acid Bacteria (LAB) and their bacteriocins can be successfully used as natural preservatives in meat products. This work aimed to investigate the effect of fresh and lyophilized starter cultures of an autochthonous bacteriocinogenic LAB strain (Lactobacillus plantarum ST153Ch: bac + culture) on the microbiological characteristics of “Alheira”, a traditional Portuguese smoked product. “Alheira” with the addition of fresh or lyophilized culture (ca. 108 cfu/g) and “Alheira” control (no bacteriocinogenic culture added) were produced by an industrial meat company. The antilisterial activity of this culture in this food matrix was investigated, with some samples being inoculated with Listeria monocytogenes (ca. 105 cfu/g). Detection of L. monocytogenes, Salmonella spp., sulphite reducing clostridia, Yersinia enterocolitica and enumeration of L. monocytogenes, Staphylococcus aureus, Bacillus cereus, Escherichia coli, Enterobacteriaceae, lactic acid bacteria, yeasts and moulds were performed immediately after production and at 3, 7, 15, 21, 28, 60 and 90 days of storage at 4 ℃, according to ISO methodologies. Also, a 16S rRNA Gene Analysis was performed of the microbial communities of “Alheira” with and without the lyophilized bacteriocinogenic culture. Pathogenic and indicator organisms were not detected or were below acceptable levels in all samples. LAB counts increased during storage and reached similar values after 15 days (ca. 1010 cfu/g) in all samples. There was a clear trend for a higher reduction of L. monocytogenes in the presence of the bioprotective culture, more pronounced during the initial 15 days of storage. From the analysis of the microbial communities of samples of “Alheiras” at different stages of fermentation, Leuconostocaceae and Lactobacillaceae predominated in all the samples and Lactobacillus was the genus more prevalent in “Alheiras” after 60 days of storage with the addition of bacteriocinogenic culture.
- Production of an antilisterial medium to be used in the industry of portuguese tradicional meat productsPublication . Macieira, Ariana; Barbosa, Joana; Albano, Helena; Teixeira, Paula
- Production of LAB bacteriocin in MRS medium and in a natural cereal medium with potential application in the food industryPublication . Macieira, Ariana; Maciel, Claudia; Albano, Helena; Morais, Alcina M M B; Teixeira, Paula
- Evaluation of a bacteriocin-producing strain of pediococcus acidilactici as a biopreservative for "alheira", a fermented meat sausagePublication . Albano, Helena; Pinho, Catarina; Leite, Daniela; Barbosa, Joana; Silva, Joana; Carneiro, Luísa; Magalhães, Rui; Hogg, Tim; Teixeira, PaulaThis study was conducted to evaluate the ability of Pediococcus acidilactici HA-6111-2, a PA-1 bacteriocinproducing lactic acid bacterium (LAB), isolated from ‘‘Alheira” to inhibit a cocktail of Listeria innocua strains during production and shelf-life of these products. The bacteriocinogenic culture reduced the Listeria population below the detection limit (1.5log CFU/g) and had no effect on the growth of the natural LAB flora or on the pH. Pathogenic organisms were not detected in any sample. The presence of some virulence factors and antibiotic resistances of the strain to be used as a bioprotective culture were investigated. P. acidilactici HA-6111-2 did not produce any of the biogenic amines tested; no formation of biofilms was observed; more L(+)lactic acid was produced than its isomer D(-); no gelatinase, DNase or lipase activity was recorded; no structural genes for the haemolysin, enterococcal surface protein, hydrolytic compounds, aggregation protein and cell-wall adhesins were detected, no significant antibiotic resistances were found. P. acidilactici HA-6111-2 appears to have potential as a bioprotective culture during ‘‘Alheira” fermentation. Moreover, a trained panel considered the protected product to be sensorially acceptable.
- Screening of bacteriocinogenic lactic acid bacteria cultures and their characterization as potential probioticsPublication . Pinto, Ana; Barbosa, Joana; Albano, Helena; Teixeira, Paula
- Production of antilisterial bacteriocin by pediococcus acidilactici HA6111-2 under different stress conditionsPublication . Engelhardt, Tekla; Albano, Helena; Kiskó, Gabriella; Mohácsi-Farkas, Csilla; Teixeira, Paula
- Phenotypic and genetic heterogeneity of lactic acid bacteria isolated from “Alheira”, a traditional fermented sausage produced in PortugalPublication . Albano, Helena; Reenen, Carol A. van; Todorov, Svetoslav D.; Cruz, Diana; Fraga, Luisa; Hogg, Tim; Dicks, Leon M.T.; Teixeira, PaulaThe aim of this study was to evaluate the phenotypic and genetic heterogeneity of lactic acid bacteria (LAB) isolated from ‘‘alheira”, a fermented sausage produced in Portugal. LAB were identified to genus and species level by phenotypic characteristics, using genus or speciesspecific primers and sequencing of the gene encoding 16S rRNA. Two-hundred and eighty-three isolates were grouped into 14 species. Lactobacillus plantarum was isolated from all sausages and Enterococcus faecalis from most of the samples. Low numbers of Lactobacillus paraplantarum, Lactobacillus brevis, Lactobacillus rhamnosus, Lactobacillus sakei, Lactobacillus zeae, Lactobacillus paracasei, Leuconostoc mesenteroides, Pediococcus pentosaceus, Pediococcus acidilactici, Weissella cibaria, Weissella viridescens and Enterococcus faecium were recorded. The genetic heterogeneity of L. plantarum and E. faecalis strains were determined by numerical analysis of DNA banding patterns obtained by RAPD–PCR. Strains of L. plantarum and E. faecalis were different from different producers. This study forms the basis from which starter cultures could be selected for production of ‘‘Alheira”.
- Inhibitory effect of lactobacillus plantarum FL75 and Leuconostoc mesenteroides FL14 against foodborne pathogens in artificially contaminated fermented tomato juicesPublication . Bah, Aissé; Albano, Helena; Barbosa, Joana; Fhoula, Imene; Gharbi, Yosra; Najjari, Afef; Boudabous, Abdellatif; Teixeira, Paula; Ouzari, HaddaTomatoes and tomato based-foods contain beneficial microorganisms and various organic acids that have important nutritional values for human. The objective of this study was to access the physiochemical properties of fermented tomatoes juices and to evaluate the competitiveness of lactic acid bacteria (LAB) against Listeria monocytogenes, Listeria innocua, and Salmonella spp., in artificially contaminated tomato juice. Microbial counting (LAB, fungi Salmonella spp., and Listeria spp.) was performed after fermentation and weekly during storage. Different organic acids (Lactic, succinic, and acetic) and ethanol were also monitored using HPLC method. Color parameters were also determined. The results showed an increase of lactic and acetic acid content, during fermentation and storage of juices inoculated with Lactobacillus plantarum and Leuconostoc mesenteroides at 25 degrees C. Besides, citric acid and ethanol revealed higher content at the end of storage compared to that registered at 4 degrees C. The pH from tomatoes juices decreased from an initial value of 4.5 to below 3.2. Alongside, foodborne pathogen population was significantly suppressed in tomatoes juices when the samples were coinoculated with LAB strains. Moreover, the inhibition of Salmonella species was faster compared to that of Listeria. After four weeks of storage at 4 degrees C, Lb. plantarum and Lc. mesenteroides showed high survival rate, while pathogenic bacteria, yeasts, and molds cell numbers decreased drastically in all the contaminated vials. This work highlights the efficiency of Lb. plantarum and Lc. mesenteroides as potential starters for developing nutritious and safe fermented tomato juice products.
- Antimicrobial potential of different propolis extractsPublication . Oliveira, Mónica; Teixeira, Helena; Barbosa, Joana; Albano, Helena; Teixeira, Paula
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