Browsing by Author "Barbosa, Joana"
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- Ability of leuconostoc lactis RK18 to prevent adhesion and invasion of human intestinal cells by foodborne pathogen listeria monocytogenesPublication . Oliveira, Mónica; Barbosa, Joana; Albano, Helena; Teixeira, Paula
- Analysis of alternative shelf life-extending protocols and their effect on the preservation of seafood productsPublication . Rezende, Lourenço Pinto de; Barbosa, Joana; Teixeira, PaulaSeafood is essential to a healthy and varied diet due to its highly nutritious characteristics. However, seafood products are highly perishable, which results in financial losses and quality concerns for consumers and the industry. Due to changes in consumer concerns, demand for healthy products has increased. New trends focusing on reducing synthetic preservatives require innovation and the application of additional or alternative strategies to extend the shelf life of this type of product. Currently, refrigeration and freezing storage are the most common methods for fish preservation. However, refrigeration alone cannot provide long shelf-life periods for fish, and freezing worsens sensorial characteristics and consumer interest. Therefore, the need to preserve seafood for long periods without exposing it to freezing temperatures exists. This review focuses on the application of other approaches to seafood products, such as biodegradable films and coating technology; superchilling; irradiation; high-pressure processing; hyperbaric storage; and biopreservation with lactic acid bacteria, bacteriocins, or bacteriophages. The efficiency of these techniques is discussed based on their impact on microbiological quality, sensorial degradation, and overall preservation of the product's nutritional properties. Although these techniques are already known, their use in the industrial processing of seafood is not widespread. Thus, the novelty of this review is the aggregation of recent studies on shelf life extension approaches, which provide useful information for the selection of the most appropriate technology and procedures and industrial innovation. Despite the fact that all techniques inhibit or delay bacterial proliferation and product decay, an undesirable sensory impact may occur depending on the treatment conditions. Although no technique appears to replace refrigeration, the implementation of additional treatments in the seafood processing operation could reduce the need for freezing, extending the shelf life of fresh unfrozen products.
- Anti-Listeria potential of bacteriocins from Lactic Acid Bacteria against persistent and non-persistent L. monocytogenesPublication . Barbosa, Joana; Carvalho, Teresa Bento de; Soares, Luís; Ferreira, Vânia; Magalhães, Rui; Teixeira, PaulaIntroduction: Listeria monocytogenes is a pathogen responsible for listeriosis, a severe foodborne infection. This bacterium is of particular concern in the food industry due to its ability to persist in food processing environments, increasing the risk of food contamination [1]. However, the mechanisms that facilitate its persistence are poorly understood. Research and development of new technologies, such as effective biocides, is essential to improve the control of L. monocytogenes in food processing environments. Objective: This work aimed to assess whether the anti-listeria activity of bacteriocins produced by different Lactic Acid Bacteria (LAB) varies concerning the persistence ability of L. monocytogenes. Methods: Antilisterial activity (AU/mL) of six LAB isolates against L. monocytogenes from fermented meat products (15 non-persistent and 17 persistent) [2] was determined. Each LAB was cultivated in de Man, Rogosa and Sharpe agar plates (MRS agar) at 30 ºC for 24 h and, subsequently, one colony of each isolate was transferred to 10 ml of MRS broth. Each L. monocytogenes strain was cultivated twice in Brain Heart Infusion broth (BHI broth) at 37 ºC for 24 h under anaerobic conditions. Discussion and conclusions: Different inhibitory activities were observed among bacteriocins produced by LAB of the same species. Overall, bacteriocin produced by Leuconostoc lactis RK18 showed less activity. Differences in inhibition were observed between L. monocytogenes strains. No differences were observed between persistent and non-persistent L. monocytogenes isolates. With one exception, all the bacteriocins investigated have been shown to have excellent antilisterial activity against L. monocytogenes strains, regardless of whether they are persistent or non-persistent in food processing environments.
- Antimicrobial potential of different propolis extractsPublication . Oliveira, Mónica; Teixeira, Helena; Barbosa, Joana; Albano, Helena; Teixeira, PaulaIntroduction: Propolis is a mixture of different types of beeswax and resins collected from plants by bees (Apis mellifera). The role of propolis in the hive is related to its mechanical properties and it is used to construct, adapt and protect the hive; its antimicrobial activity ensures an aseptic environment. Propolis is known for having antibacterial activity conferred by the presence of flavonoids, aromatic acids and esters in their composition and for the presence of ferulic and caffeic acids. Several authors reported that the activity of each chemical compound present in propolis is influenced by the extraction method. These compounds are quite soluble in ethanol, however, the extracts resulting from this solvent can only be used if the ethanol is food grade. Other solvents such as propylene glycol, glycerol and oils, as well as other techniques, have been tested and have shown promising results regarding their composition and biological activities. Discussion & Conclusions: Apparently, the solvent did not affect the pH value of the propolis extracts. Ethanol and PG allowed better extractions of the phenolic compounds presented in propolis, with similar concentration values. The antioxidant activities of all extracts were similar and their composition was identical, varying only in the content of flavonoid compounds. Caffeic acid, coumaric acid, ferulic acid, quercetin and kaempferol were identified by HPLC. Propolis extracted with ethanol and PG showed higher antimicrobial activity against several microorganisms. All propolis extracted with PG, at both temperatures, inhibited most of the microorganisms tested. However, at 50 ºC, 0.3125 μg/ml of propolis extract was enough to inhibit a large number of microorganisms. Propolis 1, extracted with PG at 50 ºC demonstrated quite promising results. As conclusion, although further tests are required, propolis extracted with PG, a compound that according to the United States FDA is Generally Recognized as Safe (GRAS), could be a promising product to be used in food industry to, for example, reduce the microbial loads of raw meats and avoid cross-contaminations.
- Antimicrobial potential of different propolis extractsPublication . Oliveira, Mónica; Teixeira, Helena; Barbosa, Joana; Albano, Helena; Teixeira, Paula
- Antimicrobial susceptibility profile of faecalibacterium prausnitzii DSM 17677 a novel probiotic candidatePublication . Machado, Daniela; Barbosa, Joana; Domingos, Melany; Almeida, Diana; Andrade, José Carlos; Gomes, Ana Maria; Freitas, Ana Cristina
- Are indeed meats sold in Portugal without clostridium difficile?Publication . Carvalho, Patrícia; Barbosa, Joana; Teixeira, Paula
- Are indeed meats sold in Portugal without Clostridium difficile?Publication . Carvalho, Patrícia; Barbosa, Joana; Teixeira, PaulaIntroduction: Clostridium difficile is a Gram-positive bacilli, spore-forming and anaerobic, found both in the environment and intestinal tracts of animals and humans. The incidence and severity of diarrhea associated with C. difficile have been increasing exponentially (Rupnik et al., 2009). C. difficile infections (CDI), which were believed to be almost exclusively nosocomial and occurring mainly in immunocompromised and elderly patients, are now becoming increasingly common among low-risk individuals (Kelly et al., 2008). In 2014, an outbreak with the hypervirulent ribotype 027 strain was reported in Portugal for the first time (Oleastro et al., 2014). Among others, this ribotype have been largely isolated from animals and food. Given the bacteria spores nature and their presence in the intestinal tract of animals, it would be expected to found C. difficile in several foods. Objective: This study aimed to detect and quantify C. difficile from different meats sold in traditional commerce and supermarkets in Porto and Lisbon (Portugal). Results & Conclusions: No C. difficile was found in any of the 143 samples analyzed. These results should not be ignored, since it is not possible to be sure if the meats analyzed, in fact, did not have C. difficile or if the methods used were not sensitive enough to detect its presence. In the absence of standardized methodologies, further studies using other detection/ quantification methods of C. difficile should be performed not only on meats, but also on other types of foods, including ready-to-eat foods. Despite no confirmed cases of foodborne diseases caused by C. difficile, the increased CDI incidence suggest that contaminated foods could/may be contributing to community- and hospital- associated CDIs.
- Behavior of foodborne pathogens in soils incorporating lactic acid bacteriaPublication . Soares, Luís; Barbosa, Joana; Teixeira, PaulaFoodborne pathogens can be introduced into the soil through various sources of contamination : the use of animal faecal matter as fertilizer, irrigation water, poor agricultural practices or naturally occurring. The ability of these microorganisms to survive in manure used as fertilizer and potentially in the soil is a threat to the safety of agricultural products. [1] Subsequently, vegetables and fruits grown on these soils can be come a source of contamination. This can lead to serious health problems for consumers, especially as they are ready-to-eat products.[2] In an attempt to minimize these problems, some studies in corporating lactic acid bacteria (LAB)-producing bacteriocins against pathogens have been reported.
- Bioactive alternatives to mitigate foodborne pathogensPublication . Moreira, Inês Azevedo; Barbosa, Joana; Albano, Helena; Teixeira, Paula