Percorrer por autor "Silva, Beatriz Nunes"
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- Cardinal parameter meta-regression models describing Listeria monocytogenes growth in brothPublication . Silva, Beatriz Nunes; Cadavez, Vasco; Teixeira, José; Ellouze, Mariem; Gonzales-Barron, UrsulaListeria monocytogenes has a high case-fatality rate, substantial research has been devoted to estimate its growth rate under different conditions of temperature, pH and water activity (aw). In this study, published findings on L. monocytogenes growth in broth were extracted and unified by constructing meta-regression models based on cardinal models for (i) temperature (CM[T]), (ii) temperature and pH (CM[T][pH]), and (iii) temperature, pH and aw (CM[T][pH][aw]). After assessing all the sources retrieved between 1988 until 2017, forty-nine primary studies were considered appropriate for inclusion. Apart from the modelling variables, study characteristics such as: type of broth (BHI, TSB, TPB), reading method (colony-forming-units, CFU; or binary-dilution optical density methods, OD), inoculum concentration and strain serotype, were also extracted. Meta-regressions based on CM[T] and CM[T][pH] were fitted on subsets of the 2009 growth rate measures and revealed that type of broth and reading method significantly modulated the cardinal parameter estimates. In the most parsimonious CM[T][pH][aw] meta-regression model, whereby the variability due to type of broth was extracted in a nested random-effects structure, the optimum growth rate μopt of L. monocytogenes was found to be lower when measured as CFU (0.947 log CFU/h; SE = 0.094 log CFU/h) than when measured as OD (1.289 log CFU/h; SE = 0.092 log CFU/h). Such a model produced the following cardinal estimates: Tmin = -1.273 °C (SE = 0.179 °C), Topt = 37.26 °C (SE = 0.688 °C), Tmax = 45.12 °C (SE = 0.013 °C), pHmin = 4.303 (SE = 0.014), pHopt = 7.085 (SE = 0.080), pHmax = 9.483 (SE = 0.080), aw min = 0.894 (SE = 0.002) and awopt = 0.995 (SE = 0.001). Integrating the outcomes from numerous L. monocytogenes growth experiments, this meta-analysis has estimated pooled cardinal parameters that can be used as reference values in quantitative risk assessment studies.
- Chemical profile and bioactivities of extracts from edible plants readily available in PortugalPublication . Silva, Beatriz Nunes; Cadavez, Vasco; Ferreira-Santos, Pedro; Alves, Maria José; Ferreira, Isabel C.F.R.; Barros, Lillian; Teixeira, José; Gonzales-Barron, UrsulaPlant extracts have been proposed as alternative biocides and antioxidants to be included in a variety of food products. In this work, to assess the potential of rosemary, lemon balm, basil, tarragon, sage, and spearmint to be used as food additives, the chemical profiles and bioactivities of such plant extracts were studied. Furthermore, to evaluate the influence of extraction methods and solvents on the chemical characteristics and bioactivities of the plant extracts, two extraction methods (solid-liquid and Soxhlet extraction) and two solvents (water and ethanol 70% (v/v)) were tested for each plant. Groupwise summary statistics were calculated by plant, extraction method, and solvent, and linear models were built to assess the main effects of those terms and their interactions on the chemical characteristics and bioactivities of the extracts. The results revealed that all factors—type of plant, extraction method and solvent—have influence on the chemical profile and antioxidant activity of the resultant extracts. Interactions between factors were also observed. Hydroethanolic Soxhlet extracts presented the least potential as biopreservatives due to their low phenolic content and reduced antioxidant capacity. Oppositely, aqueous Soxhlet extracts and hydroethanolic solid-liquid extracts showed high contents in phenolic compounds and high antioxidant activities. In particular, the hydroethanolic solid-liquid extracts of lemon balm, spearmint, and sage presented the highest phenolic and flavonoid contents, accompanied by a high antioxidant activity, and they revealed antimicrobial activity against four pathogens (S. enterica ser. Typhimurium, E. coli, L. monocytogenes and S. aureus). These results demonstrate the potential of these natural resources to be incorporated as bioactive preservatives in foods or their packaging.
- Chemical profiles and bioactivities of polyphenolic extracts of Lavandula stoechas L., Artemisia dracunculus L. and Ocimum basilicum LPublication . Silva, Beatriz Nunes; Cadavez, Vasco; Caleja, Cristina; Pereira, Eliana; Calhelha, Ricardo C.; Molina, Adriana K.; Finimundy, Tiane C.; Kostić, Marina; Soković, Marina; Teixeira, José António; Barros, Lillian; Gonzales-Barron, UrsulaThis study assessed the chemical profiles and bioactivities of the infusions, decoctions and hydroethanolic extracts of tarragon, basil and French lavender. The extracts were chemically characterised (HPLC-DAD-ESI/MS) and their bioactivities were evaluated in vitro. All extracts revealed antimicrobial, antifungal and antioxidant properties. French lavender extracts showed higher total phenolic content, regardless of the extraction method used, and antioxidant and antitumour capacities, but no anti-inflammatory action. All basil and two of the tarragon extracts revealed anti-inflammatory power. Thus, tarragon, basil and French lavender extracts may be considered for inclusion in foods, as preservatives or functional ingredients. Nonetheless, further studies must be conducted to evaluate the pharmacokinetic parameters of the bioactive compounds.
- Correction: Silva et al. Chemical Profile and Bioactivities of Extracts from Edible Plants Readily Available in Portugal. Foods 2021, 10, 673Publication . Silva, Beatriz Nunes; Cadavez, Vasco; Ferreira-Santos, Pedro; Alves, Maria José; Ferreira, Isabel C.F.R.; Barros, Lillian; Teixeira, José António; Gonzales-Barron, UrsulaThe authors found a mistake in the original paper [1]. Throughout the article, French lavender was wrongfully named rosemary. Rosemary was not used in the original study. Below are provided the full details of the changes in the Figures, Tables, and text. The authors sincerely apologise for any inconvenience caused and state that the scientific conclusions are unaffected. The original publication has been updated.
- Dynamic modelling to describe the effect of plant extracts and customised starter culture on Staphylococcus aureus survival in goat's raw milk soft cheesePublication . Silva, Beatriz Nunes; Coelho-Fernandes, Sara; Teixeira, José António; Cadavez, Vasco; Gonzales-Barron, UrsulaThis study characterises the effect of a customised starter culture (CSC) and plant extracts (lemon balm, sage, and spearmint) on Staphylococcus aureus (SA) and lactic acid bacteria (LAB) kinetics in goat's raw milk soft cheeses. Raw milk cheeses were produced with and without the CSC and plant extracts, and analysed for pH, SA, and LAB counts throughout ripening. The pH change over maturation was described by an empirical decay function. To assess the effect of each bio-preservative on SA, dynamic Bigelow-type models were adjusted, while their effect on LAB was evaluated by classical Huang models and dynamic Huang-Cardinal models. The models showed that the bio-preservatives decreased the time necessary for a one-log reduction but generally affected the cheese pH drop and SA decay rates (logD(ref) = 0.621-1.190 days; controls: 0.796-0.996 days). Spearmint and sage extracts affected the LAB specific growth rate (0.503 and 1.749 ln CFU/g day(-1); corresponding controls: 1.421 and 0.806 ln CFU/g day(-1)), while lemon balm showed no impact (p > 0.05). The Huang-Cardinal models uncovered different optimum specific growth rates of indigenous LAB (1.560-1.705 ln CFU/g day(-1)) and LAB of cheeses with CSC (0.979-1.198 ln CFU/g day(-1)). The models produced validate the potential of the tested bio-preservatives to reduce SA, while identifying the impact of such strategies on the fermentation process.
- Effect of lemon balm and spearmint extracts on the survival of S. aureus in goat’s raw milk cheesePublication . Silva, Beatriz Nunes; Coelho-Fernandes, Sara; Teixeira, José António; Cadavez, Vasco; Gonzales-Barron, UrsulaA previous investigation from our research group has revealed that lemon balm and spearmint hydroethanolic extracts present high inhibitory capacity in vitro against S. aureus. Raw milk cheeses have exhibited moderate prevalence of S. aureus, thus imposing a safety issue for consumers. In this sense, our work aimed to evaluate the antibacterial effect of lemon balm and spearmint extracts against S. aureus in goat’s raw milk cheeses during maturation, and to characterise the survival kinetic parameters of this pathogen by extended Bigelow models.
- Effects of essential oils on escherichia coli inactivation in cheese as described by meta-regression modellingPublication . Silva, Beatriz Nunes; Cadavez, Vasco; Teixeira, José; Gonzales-Barron, UrsulaThis article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). The growing intention to replace chemical food preservatives with plant-based antimicrobials that pose lower risks to human health has produced numerous studies describing the bactericidal properties of biopreservatives such as essential oils (EOs) in a variety of products, including cheese. This study aimed to perform a meta-analysis of literature data that could summarize the inactivation of Escherichia coli in cheese achieved by added EOs; and compare its inhibitory effectiveness by application method, antimicrobial concentration, and specific antimicrobials. After a systematic review, 362 observations on log reduction data and study characteristics were extracted from 16 studies. The meta-regression model suggested that pathogenic E. coli is more resistant to EO action than the non-pathogenic type (p 0.0001), although in both cases the higher the EO dose, the greater the mean log reduction achieved (p 0.0001). It also showed that, among the factual application methods, EOs’ incorporation in films render a steadier inactivation (p 0.0001) than when directly applied to milk or smeared on cheese surface. Lemon balm, sage, shallot, and anise EOs showed the best inhibitory outcomes against the pathogen. The model also revealed the inadequacy of inoculating antimicrobials in cheese purposely grated for performing challenge studies, as this non-realistic application overestimates (p 0.0001) the inhibitory effects of EOs.
- Estudio de la aplicación en seguridad alimentaria de extractos de plantas comunes en la Región Mediterránea con capacidad antimicrobiana una evaluación meta-analíticaPublication . Bonilla-Luque, Olga María; Possas, Arícia; Silva, Beatriz Nunes; Cadavez, Vasco; Valero, Antonio; Gonzales-Barron, UrsulaLa contaminación microbiana en alimentos durante sus diferentes etapas de producción supone un reto para las industrias alimentarias. Como pilar importante en seguridad alimentaria, la preservación de alimentos se ha llevado a cabo mediante diferentes conservantes sintéticos tradicionales. Sin embargo, el interés en aceites esenciales como biopreservativos es recientemente visible, dada su mayor sostenibilidad medioambiental y seguridad [1]. Bajo esta perspectiva, entre 2000-2020 se ha llevado a cabo una prolífica labor de investigación relativa a la aplicación de aceites esenciales en alimentos.
- Extraction, chemical characterization, and antioxidant activity of bioactive plant extractsPublication . Silva, Beatriz Nunes; Cadavez, Vasco; Ferreira-Santos, Pedro; Teixeira, José António; Gonzales-Barron, UrsulaNatural extracts have been proposed as preservatives to increase the safety of various food products. In this work, the phytochemical and antioxidant profiles of French lavender (Lavandula stoechas), lemon balm, basil, tarragon, salvia, and spearmint extracts were studied. The results show that hydroethanolic extracts may be more effective as biopreservatives if moderate temperatures are used in the extraction process, as they revealed higher phenolic content. More specifically, the results also show that lemon balm extracts present a great potential to be used as biopreservatives, due to their high-level phenolic and flavonoid contents and antioxidant activity.
- Extracts from red eggplant: impact of ohmic heating and different extraction solvents on the chemical profile and bioactivityPublication . Ferreira-Santos, Pedro; Duca, Anna Barbara; Genisheva, Zlatina; Silva, Beatriz Nunes; Biasio, Filomena de; Botelho, Cláudia; Rocha, Cristina M.R.; Gorgoglione, Domenico; Teixeira, José AntónioEggplants contain a multitude of biocompounds with nutritional and/or biological activities. The objective of this work was to study the nutritional, chemical and bioactive value of red eggplant from Rotonda, Italy. Ohmic heating (OH) was compared to conventional heating, as different solvents were used (water, ethanol 30, 50, and 90%and methanol) for biocompounds extraction. Extracts were evaluated for their total phenolic compounds, antioxidant and antibacterial activities, and its toxicity was assessed in cells, L929 and Caco-2. The nutritional characterization of Rotonda’s eggplant demonstrated that it is rich in carbohydrates (65%), fiber (12.5%), proteins (13%), lipids (7.6%) and minerals. Potassium is the mineral with the highest concentration in the red eggplant (27.24 mg/g). Phenolic composition of the obtained extracts was dependent on the extraction method, as well as on the solvent. The use of OH method increased the extraction of biocompounds, especially when using 50% of ethanol as solvent. The main phenolic compounds found in the extracts of this eggplant variety were ellagic acid, p-coumaricic acid, epicatechin, narginin, taxifolin and kaempferol. Antioxidant activity was positively correlated with the total amounts of phenolics. Red Eggplant extracts showed activity against Gram-negative bacteria (E. coli and S. enterica), however, they did not demonstrate activity against Gram-positive bacteria. The extracts obtained did not show cytotoxic effects in fibroblast and colorectal studied cells. Ohmic heating is a sustainable technology that increases the extraction yield of biocompounds, with reduced energy consumption and the resulting extracts show low toxicity and high biological activity.
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