Browsing by Author "Cadavez, Vasco"
Now showing 1 - 10 of 251
Results Per Page
Sort Options
- An alternative framework to conduct inferential statistics for low microbial counts in foods: the poisson-gamma regressionPublication . Gonzales-Barron, Ursula; Cadavez, Vasco; Butler, FrancisThe objective of this article was to compare four Poisson-gamma regression models to assess the effect of chilling on the concentration of coliforms from beef carcasses. A total of 600 carcasses were sampled before and after chilling at eight large Irish abattoirs, and the total coliforms were determined. With a coded variable (pre-chill/post-chill) as treatment, and extracting the variability of batches nested in abattoirs, random-effects models confirmed that chilling had a decreasing effect on the overall recovery of coliforms. Furthermore, the expected coliforms concentrations on pre-chill and post-chill carcasses were estimated on a CFU/cm2 scale, as well as their between-batch variability. This study introduced an alternative conceptual framework that can find interesting applications in stochastic risk assessment and in the design of more efficient sampling plans.
- An assessment of the processing and physicochemical factors contributing to the microbial contamination of salpicão, a naturally-fermented Portuguese sausagePublication . Cadavez, Vasco; Gonzales-Barron, Ursula; Pires, P.; Fernandes, E.; Pereira, Ana Paula; Gomes, Aline; Araújo, José Pedro; Lopes-da-Silva, M.F.; Rodrigues, Paula; Fernandes, Conceição; Saavedra, Maria José; Butler, Francis; Dias, TeresaComplete microbiological, physicochemical and environmental longitudinal data were obtained from factory surveys in order to elucidate risk factors leading to the survival of Enterobacteriaceae, Staphylococcus aureus and Listeria monocytogenes in salpicão sausage. A total of six batches were surveyed from two factories; one added nitrite and polyphosphates in their formulation (Factory II). The addition of polyphosphates slowed down fermentation, which favoured the increase in Enterobacteriaceae (∼0.5 log CFU/g), S. aureus (∼0.5 log CFU/g) and L. monocytogenes (∼70 CFU/g) until maceration. Maceration should be regarded as a critical stage in the control of S. aureus in salpicão, as longer maceration (p = 0.033), higher temperatures of maceration (p = 0.018) and pH of macerated meat (p = 0.079) led to higher S. aureus counts in the final product. The main hurdle controlling S. aureus in salpicão is the pH. For L. monocytogenes and Enterobacteriaceae, at least three hurdles hinder their viability: low Aw (p = 0.010; 0.012), smoking (p < 0.0001; 0.020) and nitrite (p = 0.158; 0.105). Cross-contamination, especially during mixing, should be avoided as it is an important factor explaining the increase in Enterobacteriaceae (p = 0.041), S. aureus (p = 0.015) and L. monocytogenes (p = 0.082) on a batch basis. There is a need to optimise the acidification process and reinforce good hygiene practices
- An extend bigelow-type meta-regression model descring the heat resistance of neosartorya sporesPublication . Gonzales-Barron, Ursula; Cadavez, Vasco; Alvarenga, Verônica O.; Prado-Silva, Leonardo; Sant'Ana, Anderson S.A meta-regression based on an extended-Bigelow equation was adjusted to 326 D-values of Neosartorya spp., taken from the literature, in order to summarise its heat resistance parameters. As the meta-regression accommodated relevant study characteristics, it was possible to estimate D*-values and z-values of temperature, pH and °Brix for the various beverages, inactivation methods, fruits and preservative use/no use.
- Análise sensorial de vários tipos de hidromelPublication . Gomes, Teresa; Dias, Teresa; Andrade, João Verdial; Cadavez, Vasco; Morais, Jorge Sá; Ramalhosa, Elsa; Estevinho, Leticia M.A região de Trás-os-Montes e uma das grandes produtoras de mel no pais. No entanto, existe dificuldade em escoar a produção surgindo o hidromel como uma alternativa possível para ultrapassar este problema. Com base em resultados obtidos pela nossa equipa, este trabalho teve como objective avaliar as características sensoriais do hidromel produzido a escala piloto. Resultados anteriores indicam que a levedura Saccharomyces cerevisiae Fermol® Reims Champagne (Pascal Biotech®) á a mais indicada para a fermentação do hidromel. As condições ideais para a produção de hidromel obtidas com base no desenho experimental foram: temperatura entre os 24°C e os 29°C e concentração de sais entre 85 e 100 g/hL.
- Anti-listerial activity of lactic acid bacteria isolated from artisanal cheeses produced in the State of Minas Gerais, BrazilPublication . Campagnollo, Fernanda B.; Margalho, Larissa P.; Kamimura, Bruna A.; Alvarenga, Verônica O.; Cadavez, Vasco; Gonzales-Barron, Ursula; Sant'Ana, Anderson S.Introduction: Brazilian artisanal cheeses, among them Minas cheeses, are highly appreciated by consumers. Nonetheless, some cheeses have been regularly found to harbour high-risk pathogens, such as Listeria monocytogenes, mainly arising from their elaboration with raw milk and informal production. However, cheese matrices are complex systems whose microbial competing factors (i.e., indigenous lactic acid bacteria (LAB)) and intrinsic properties (acidity, temperature, and water activity) can act as effective hurdles against L. monocytogenes proliferation. Purpose: The aim of this study was to evaluate the capacity of LAB strains isolated from Minas artisanal cheeses as anti-listerial agents. Methods: A total of 891 LAB strains were isolated from 244 Minas artisanal cheese samples (466 using MRS agar (MRSLAB) and 425 using M17 agar (M17LAB)), which were tested qualitatively for anti-listerial activity by the deferred antagonism assay at 30oC (24 h). Two L. monocytogenes strains, serotypes 1/2b and 4b, isolated from cheese and crude milk, respectively, were used. LAB strains with positive anti-listerial activity at 30oC were further tested at 7oC (10 days). Results: MRSLAB strains presented significantly better anti-listerial activity at 30oC (73.0% and 70.8% for serotypes 1/2b and 4b, respectively) compared to M17LAB strains (21.2% and 23.1%, respectively), and there was no significant difference between listeria serotypes (P<0.05). Selected MRSLAB and M17LAB strains were able to keep anti-listerial activity at 7oC, with no significant differences between MRSLAB (96.8% and 97.2% for listeria 1/2b and 4b, respectively) and M17LAB (95.2% and 96.8%, respectively) or between Listeria serotypes (P<0.05). Significance: These results suggested that LAB isolated from Minas cheeses using MRS agar present a better inhibitory effect against L. monocytogenes at different temperatures. These strains can be used as starter cultures in order to inhibit pathogen survival.
- Arthropod biodiversity associated to European sheep grazed pasturesPublication . Garcia, Rosa; Peric, Tanja; Cadavez, Vasco; Ko, Nathanael; Cerqueira, Joaquim; Stanganello, R. Pietro; Fernandes, E.; Celaya, Rafael; Gonzales-Barron, Ursula; Baratta, MarioWe analysed the biodiversity of foliage arthropods in nine sheep grazed pasturelands in five European countries. During the maximum flowering period in 2018, entomofauna was collected in 4-6 areas within each pasture, performing 6 transects/area and 25 sweeps per transect. Multivariate analyses tested the differences in total arthropod community composition among degrees of intensification, bioregions and types of pastures. A total of 51,474 arthropods from 3 classes, 17 orders and 95 taxonomical groups were recorded. Univariate analyses revealed that total arthropod abundance was higher in extensive than in intensive systems (P<0.01). It also differed between bioregions (higher in Alpine than in Continental, P<0.05) and between types of pastures (higher in mountain than in lowland pastures where animals are supplemented, P<0.05). Total taxa richness was not influenced by any of the three factors. However, multivariate analyses indicated that community composition differed among intensive and extensive systems, bioregions and types of pastures (P<0.001). The greatest differences occurred between Alpine and Mediterranean (P<0.001), and Mediterranean and Continental pastures (P<0.05), as well as between lowland seminatural and improved pastures (P<0.05), and seminatural and mountain pastures (P<0.001). These results reveal the complex and varied communities associated to the diverse sheep systems and valorise the role of the mo
- Arthropod biodiversity associated to European sheep production systemsPublication . Rosa García, Rocío; Peric, Tanja; Cadavez, Vasco; Geß, Andreas; Cerqueira, Joaquim; Gonzales-Barron, Ursula; Baratta, MarioThe rural territories linked to European sheep systems still cover wide areas and provide multiple ecosystems services although the current situation of the associated biodiversity is not fully understood. In this study the foliage arthropods (including pollinators), the vegetation cover and height, the number of flowers and plant species richness were evaluated in 9 sheep grazed lands from 5 EU countries with different livestock management strategies and dominant vegetation. The total abundance of arthropods, the abundance of Diptera and Heteroptera, sward height and plant species richness were higher in more extensive than in more intensively managed farms. The total abundance and the abundance of most of the orders were highest in mountain areas (MP) and lowest in improved pastures (IMP) whereas the total arthropod richness showed no differences and the richness of pollinators was lower in IMP than in MP (p < 0.01) and semi-natural pastures (SN, p < 0.01). The grass cover was higher in IMP than in the rest of the areas whereas forb cover was higher in SN than in IMP (p < 0.01). The plant species richness peaked in MP whereas the number of flowers showed no significant differences. Sward height correlated positively with forb cover, plant species richness, the richness of the whole arthropod community, the abundance of several orders like Araneae, Diptera or Homoptera, as well as with the richness of the pollinator community. The community composition of the total arthropod fauna (p < 0.01) and the pollinators in particular (p < 0.05) differed between management strategies and more diverse groups were linked to the areas under more extensive management. Both communities (total and pollinators) also differed in composition between the types of vegetation (p < 0.01) and less diverse assemblages with low abundant taxa were associated to IMP and SN whereas more diverse groups were linked to MP and grassland-forest (WP) in both cases. A better understanding of the flora-fauna dynamics in sheep grazed pasturelands is essential for the proper conservation of the biodiversity and other ecosystem services, as well as for the maintenance of sustainable sheep systems relying on the natural resources.
- Beef burger patties incorporated with Boletus edulis extracts: lipid peroxidation inhibition effectsPublication . Barros, Lillian; Barreira, João C.M.; Grangeia, Cátia; Batista, Cátia Emanuela Oliveira; Cadavez, Vasco; Ferreira, Isabel C.F.R.The objective of this study was to analyse the lipid peroxidation inhibition in beef burgers after incorporation of Boletus edulis extracts in different concentrations. Beef burgers samples were stored for 8 days, and chemical and nutritional parameters, including the profile in free fatty acids, were evaluated. Furthermore, the inhibition of thiobarbituric acid reactive substances (TBARS) formation, free radical scavenging activity and reducing power were determined. Polyunsaturated fatty acids arachidonic (C20:4n6) and cis-5,8,11,14,17-eicosapentaenoic (C20:5n3) acids were protected in the presence of mushroom extract. The antioxidant potential increased with the amount of extract added to beef burgers, giving higher radical scavenging properties and TBARS inhibition capacity. These findings indicated that beef burgers patties were protected from lipid peroxidation in the presence of mushroom extract.
- Beef quality evaluation systemPublication . Teixeira, Cátia; Cadavez, Vasco; Monteiro, Fernando C.Applying computer vision in meat quality evaluation has been an active area of research in recent years. Accurate segmentation of beef-marbling images plays an important role in making the correct decision on beef-marbling score in an automatic beef quality grading system. The purpose of this study was to develop a new segmentation method to correctly separate the fat flecks from the muscle in the rib-eye region in a beef image. The key idea was to measure the percentage of marbling in the muscle to obtain a beef quality evaluation system.
- Beef quality evaluation systemPublication . Teixeira, Cátia; Cadavez, Vasco; Monteiro, Fernando C.The accurate accurate accurate accurate segmentation segmentation segmentation segmentation segmentationof beef -marbling marbling marblingmarbling images images playsplays plays an importantimportant important important role role in making making makingthe correct correct correct correctdecision decision decision decision on beef beefbeef-marbling marbling marbling marblingscore score scorein an automatic automatic automatic beef beef quality quality quality grading grading grading gradingsystemsystem system .The purposepurpose purposepurpose purposeof this thisstudy study studyis to develop develop develop developanew segmentation segmentation segmentation segmentation segmentation method method to correctly correctly correctly correctly separate separate separate separate the fat flecksflecks flecks flecksfrom fromthe musclemuscle muscle musclein the rib -eye region region region of beef images images .