Percorrer por autor "Coelho-Fernandes, Sara"
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- 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.
- Effect of physicochemical characteristics of lamb meat on its microbiological deteriorationPublication . Félix-Oliveira, Diogo; Coelho-Fernandes, Sara; Lorenzo Rodriguez, Jose Manuel; Cadavez, Vasco; Gonzales-Barron, UrsulaA common strategy to improve the tenderness of lamb meat of autochthonous Portuguese breeds is to mature vacuum-packed (VP) meat for ~7 days. Nonetheless, the extent to which microbial spoilage is delayed by VP depends upon the meat intrinsic properties. The objective of this study was to appraise how the growth rate of deteriorating bacteria in VP lamb meat is affected by the initial microbial load and physicochemical characteristics.
- Effect of Sage (Salvia officinalis L.) Extract on the Survival of Staphylococcus aureus in Portuguese Alheira Sausage during MaturationPublication . Coelho-Fernandes, Sara; Rodrigues, Gisela; Faria, Ana Sofia; Caleja, Cristina; Pereira, Eliana; Pinela, José; Carocho, Márcio; Barros, Lillian; Cadavez, Vasco; Gonzales-Barron, UrsulaThe objective of this study was to assess the effect of sage (Salvia officinalis L.) extract on the survival of Staphylococcus aureus in a Portuguese non-ready-to-eat meat product (alheira sausage). Alheira batter was produced, mixed with 0.0%, 0.5%, 1.0%, or 1.5% of lyophilised sage extract, and stuffed in natural casings. Sausages were then individually inoculated with S. aureus and left to ferment/mature at 10 °C/85% RH for 10 days. Sage extract was found to inactivate S. aureus (p < 0.001) with no significant differences between doses. At the 10th day of maturation, S. aureus decreased in 1.146 log CFU/g (SE = 0.065 log CFU/g) in alheiras mixed with 0.5–1.0% sage extract. Nonetheless, this extract retarded the growth of indigenous lactic acid bacteria during maturation. The higher the dose, the greater the effect (p < 0.001).
- Evolución de los microorganismos de dterioro en carne de cordero envasada al vacío de origen portuguésPublication . Félix-Oliveira, Diogo; Coelho-Fernandes, Sara; Gonzales-Barron, Ursula; Cadavez, VascoEn la Unión Europea, existen un conjunto de marcas de calidad asociadas a la carne, las cuales tienen por finalidad no sólo certificar su calidad sino también aumentar el rendimiento de los productores, en vista a que sus intereses confluyen con los intereses del consumidor moderno que procura garantías de calidad y sanidad. En Portugal, el Decreto Ley 147/2006 aprobó las condiciones higiénicas y técnicas a ser observadas en la distribución y venta de las carnes y sus productos, estableciendo 7ºC como la temperatura máxima de distribución y conservación de carnes frescas. Por otro lado, la maduración de la carne, que ocurre durante almacenamiento refrigerado a 0 - 4ºC, es esencial para mejorar la ternura de la misma. En el caso de la carne de cordero, a los 7 días de maduración se alcanza casi el 80% de su máximo potencial de ternura (Prates, 2000). Sin embargo, durante esta maduración – favorable a la calidad sensorial – también se da a cabo el deterioro microbiano debido a la proliferación de bacterias psicrotróficas, ácido-lácticas, Pseudomonas, Clostridium, etc. (Berruga et al., 2005). Una de las estrategias para prolongar el tiempo de vida de la carne es la aplicación de envasado al vacío, la cual puede retardar moderadamente el deterioro microbiano. Sin embargo, se debe tener en cuenta que la tasa de retardo depende principalmente de la calidad microbiológica inicial de la carne y su pH. El objetivo de este estudio fue evaluar la evolución de microorganismos indicadores de deterioro (mesófilos, psicrotróficos, bacterias ácido-lácticas y Pseudomonas spp) en carne de cordero envasada al vacío, durante almacenamiento refrigerado a 4º±1ºC. El deterioro microbiano en carnes provenientes de dos razas portuguesas, Bordaleira-de-Entre-Douro-e-Minho (BEDM) y Churra-Galega-Bragançana (CGB), fue comparado.
- Evolution of spoilage microorganisms in vacuum-packed lamb meat from two portuguese breedsPublication . Gonzales-Barron, Ursula; Félix-Oliveira, Diogo; Coelho-Fernandes, Sara; Santos-Rodrigues, Gisela; Lorenzo Rodriguez, Jose Manuel; Cadavez, VascoAlthough meat ageing at cold storage is essential to improve meat tenderness (Prates, 2000), the natural process of microbial spoilage takes place at the same time due to the proliferation of psychrotrophic bacteria, lactic acid bacteria, Pseudomonas spp. and Clostridium spp. (Berruga et al., 2005). A known strategy to moderately extend the shelf-life of meat is vacuum packaging. However, the spoilage retardation rate mainly depends on the initial microbiological quality of meat as well as its initial pH. The objective of this study was to evaluate the evolution of lactic acid bacteria and spoilage microorganisms (i.e., mesophiles, psychrotrophic bacteria and Pseudomonas spp.) in vacuum-packed lamb meat during cold storage at 4ºC. The microbial spoilage in meat originating from two Portuguese ovine breeds, Bordaleira- de-Entre-Douro-e-Minho (BEDM) and Churra-Galega-Bragançana (CGB), was compared.
- Microbial contamination of lamb carcasses and meat from autochthonous portuguese breedsPublication . Coelho-Fernandes, Sara; Félix-Oliveira, Diogo; Gonzales-Barron, Ursula; Cadavez, VascoDespite the high consumption of lamb meat in Portugal, there is limited information on its microbiological safety. The objective of this study was to evaluate the levels of hygiene indicator microorganisms and occurrence of pathogens on lamb carcasses and meat from two autochthonous Portuguese breeds, Bordaleira-de-Entre-Douro-e-Minho (BEDM) and Churra-Galega-Bragançana (CGB); and evaluate possible associations among these bacterial groups within slaughter batches.
- Microbial deterioration of lamb meat from European local breeds as affected by its intrinsic propertiesPublication . Gonzales-Barron, Ursula; Coelho-Fernandes, Sara; Rodrigues, Gisela; Choupina, Altino; Bermúdez Piedra, Roberto; Osoro, Koldo; Celaya, Rafael; García, Rocío R.; Peric, Tanja; Bianco, Silvia del; Piasentier, Edi; Chiesa, Francesco; Brugiapaglia, Alberto; Battaglini, Luca; Baratta, Mario; Bodas, Raúl; Lorenzo Rodriguez, Jose Manuel; Cadavez, VascoAlthough sheep meat has a small share of 1.5 % of the total meat production in the EU, sheep farming is of great importance to rural development and the environment. Enhancing the quality of lamb meat of local breeds is essential to ensure both profitability for sheep producers and the conservation of endangered breeds. This study aimed to (i) characterise the evolution of spoilage microorganisms in refrigerated vacuum-packed lamb meat from a total of 10 farms housing 8 local breeds of Portuguese, Spanish, Italian and Slovenian origin raised in intensive, extensive or semi-extensive regime; and (ii) elucidate how intrinsic properties of meat can affect its microbial spoilage. Cold carcass weight (CCW), ultimate pH (pH24) and proximate analysis were quantified on carcass/meat from each of the 285 animals raised and slaughtered for this purpose; while mesophiles, lactic acid bacteria, Pseudomonas spp. and psychrotrophic bacteria were enumerated during 15-day storage at 4 °C. Substantial variability in all attributes were found between the ten farms. CCW of intensively-raised lambs (21.4 kg; 95 % CI: 20.6–22.1 kg) were higher (p lt 0.05) than the ones in semi-extensive regime (14.9 kg; 95 % CI: 14.4–15.4 kg), and in turn these were heavier (p lt 0.05) than the extensively raised lambs (12.4 kg; 95 % CI: 12.0–12.7). Mean contents of protein (76.5–87.4% db), fat (3.78–13.1% db) and ashes (4.62–5.65% db) in lamb meat were highly dependent on the farm. Although meat from some farms was associated to higher microbial levels, in general, microbial growth was found to be modulated by intrinsic properties of meat. Higher pH24 (p lt 0.05), moisture (p lt 0.05), protein content (p lt 0.05) and ashes content (p lt 0.01) accelerated spoilage rate; whereas meat from heavier carcasses (p lt 0.001) and of higher fat content (p lt 0.01) presented slower growth of spoilage bacteria. In order to improve the microbial quality of lamb meat, animal handling must be enhanced to minimise pre-slaughter stress; slaughtering practices and hygiene must be improved; and a carcass classification system could be adopted towards the selection of fatter animals and chilled carcasses of optimal pH24.
- Microbial deterioration of lamb meat of portuguese origin as affected by its intrinsic propertiesPublication . Cadavez, Vasco; Gonzales-Barron, Ursula; Félix-Oliveira, Diogo; Coelho-Fernandes, Sara; Rodrigues, GiselaIn Portugal, sheep and goat meat production constitutes 2.8% of the total meat production, with a self-sufficiency of ~82%. The main autochthonous sheep breeds exploited for meat production are Churra-Galega-Bragançana (CGB) and Bordaleira-de-Entre-Douro-e-Minho (BEDM), whose quality must be optimised in order to ensure adequate income levels for sheep producers. The study aimed to characterise the evolution of spoilage microorganisms in refrigerated vacuum-packed (VP) lamb meat from BEDM and CGB breeds; and elucidate how intrinsic properties of meat can affect its microbial spoilage. Meat from BEDM breed presented higher (p<.0001) populations of mesophiles, lactic acid bacteria, Pseudomonas spp. and psychrotrophic bacteria, since its higher ultimate pH (means: 5.77 for BEDM vs. 5.58 for CGB) accelerated spoilage rate (p<.0001). While water activity and protein content were not found to modulate microbial deterioration (p>0.05), the growth of spoilage bacteria was found to be exacerbated by higher moisture (p<.0001) and higher ash content (p<0.001). By contrast, a higher fat content retarded (p<.0001) the growth of spoilage bacteria in VP lamb meat. In order to extend the shelf-life of Portuguese-origin lamb meat, animal handling must be enhanced to minimise pre-slaughter stress, and a carcass classification system should be adopted towards the selection of fatter animals and chilled carcasses of optimal ultimate pH.
- Microbiological and physicochemical assessment of artisanally produced “Alheira” fermented sausages in Northern PortugalPublication . Coelho-Fernandes, Sara; Zefanias, Odete; Rodrigues, Gisela; Faria, Ana Sofia; Fernandes, Ângela; Barros, Lillian; Cadavez, Vasco; Gonzales-Barron, UrsulaAlheira is a traditional non-ready-to-eat sausage produced mainly in northern Portugal. The objective of this study was to evaluate the associations between some relevant physicochemical and microbiological attributes of alheiras produced by different regional producers. Finished products from 8 regional factories amounting to 40 samples were analyzed. Counts of mesophiles, lactic acid bacteria, Staphylococcus aureus, presumptive Clostridium perfringens, and Salmonella spp., as well as pH, water activity (aW), and proximate analysis were determined. Principal component analysis (PCA) of these variables was conducted to construct quality maps. Three meaningful components were extracted, accounting for 63% of data variability. PC1 (26% data variability) was positively associated with LAB, mesophiles, and S. aureus, characterizing therefore longer fer- mentation. PC2 (22% data variability) correlated negatively with moisture, aW and positively with C. perfringens, and thus has been linked to greater dehydration of sausages. PC3 (15% data varia- bility) correlated positively with pH and protein content, implying the use of more meat in the formulation. This preliminary work has identified three quality factors underpinning the variabil- ity in artisanal alheiras; and has also highlighted the need to implement better microbiological control and process standardization during the production of artisanal alheiras.