Browsing by Author "Pintado, Cristina Santos"
Now showing 1 - 10 of 35
Results Per Page
Sort Options
- Association between a case study of asymptomatic ovine listerial mastitis and the contamination of soft cheese and cheese processing environment with listeria monocytogenes in portugalPublication . Pintado, Cristina Santos; Grant, Kathie; Halford-Maw, Robin; Hampton, Mike D.; Ferreira, Maria A.S.S.; McLauchlin, JimFor 5 months, the udders of milking ewes, raw ewe’s milk, cheese, and the plant and environment of a cheese manufacturer in Portugal were investigated using standard methods for the presence of Listeria spp. An association between subclinical mastitis and Listeria monocytogenes in a single lactating sheep was investigated by visual inspection of udders for signs of inflammation, application of somatic cell counts, the California mastitis test, pH measurement to milk, and culture of L. monocytogenes and Staphylococcus spp. To track the routes of contamination by L. monocytogenes, 103 isolates were characterized by molecular serotyping and amplified fragment length polymorphism, and a selection was further tested by pulsed-field gel electrophoresis. This study provides molecular and epidemiological evidence tracking the persistence of a single L. monocytogenes strain causing a subclinical udder infection without obvious inflammation in a single ewe. This infection was the likely source of contamination of raw milk that was subsequently used to produce unpasteurised milk cheese and resulted in a single strain of this bacterium colonizing the processing environment and the final cheese product.
- Control of pathogenic and spoilage microorganisms from cheese surface by whey protein films containing malic acid, nisin and natamycinPublication . Pintado, Cristina Santos; Ferreira, Maria A.S.S.; Sousa, IsabelThe inhibitory effects of nisin, natamycin and malic acid, incorporated in whey protein films with pH 3, were investigated alone or with addition of sucrose esters, Tween80 or EDTA. Water vapour permeability measurements and mechanical and rheological tests were also assessed. EDTA and Tween80 did not significantly (P < 0.05) influence the inhibitory activity of films against Pseudomonas aeruginosa and Yarrowia lipolytica in contrast with the improved effect against Listeria monocytogenes, Penicillium commune and Penicillium chrysogenum. Sucrose esters reduced significantly (P < 0.05) the inhibitory effect for Y. lipolytica and Penicillium spp. The present work provides an antimicrobial film formulation with potential to be a hurdle against spoilage and pathogenic microorganisms isolated from cheese surface.
- Degradação de compostos fenólicos por estirpes de Lactobacillus isoladas de águas russasPublication . Lourenço, Catarina; Rafael, Carla; Mello-Sampayo, Cristina; Pintado, Cristina Santos; Santos, Teresa; Catulo, Luís; Oliveira, Maria Manuela; Brito, Dulce; Peres, CidáliaAs águas russas, principal resíduo da indústria de extracção do azeite, são caracterizadas por uma elevada carga orgânica poluente constituindo, por esta razão, um dos mais graves problemas ambientais dos países da bacia mediterrânea. São particularmente ricas em compostos fenólicos, lípidos e açúcares e apresentam teores mínimos de compostos azotados. O seu potencial biológico e energético é importante, pelo que se estudou a possibilidade de serem usadas como meio de cultura para produção de inóculos lácticos para a indústria de preparação de azeitona de mesa. Foram estudadas várias fontes de compensação de azoto, bem como vários tipos de meio, líquido ou sistema bifásico, com vista à maximização da capacidade de degradação de compostos fenólicos por bactérias lácticas (BL). Foram também estudados alguns dos factores de adaptação das BL às condições de stress fenólico. Concluiu-se que a degradação dos compostos fenólicos e a produção de ácido láctico depende do tipo e da concentração de azoto. Verificou-se que as BL possuem um mecanismo de adaptação ao stress fenólico, baseado em alterações dos seus componentes celulares.
- Essential oils of Lavandula stoechas subsp. luisieri as antifungal agent against fungi from strawberry tree fruitPublication . Domingues, Joana Lopes; Delgado, F.M.G.; Gonçalves, José Carlos; Pintado, Cristina SantosEssential oils of Lavandula stoechas subsp. luisieri as antifungal agent against fungi from strawberry tree fruit
- Essential oils of Lavandula stoechas subsp. luisieri as antifungal agent against fungi from strawberry tree fruitPublication . Domingues, Joana Lopes; Delgado, F.M.G.; Gonçalves, José Carlos; Pintado, Cristina SantosL. stoechas subsp. luisieri is one of the five spontaneous species of the genus Lavandula that occurs spontaneously in Portugal. The chemical profile and antifungal activity of L. stoechas subsp. luisieri essential oils were investigated. The essential oil of two phenological stages was isolated by hydrodistillation and their chemical components analyzed by GC-FID/GC-MS. The minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) of both essential oils were determinate to verify antifungal activity against different strains of fungi isolated from strawberry tree. The fungi tested were Aspergillus carbonarius, Rhizopus stolonifer, Penicillium brevicompactum, Aureobasidium pullulans and Saccothecium rubi. Essential oils were characterized by a high percentage of oxygenated monoterpenes (46-64%) such as trans-α-necrodyl acetate (12.58%), fenchone (5.97%), 1,8-cineole (4.84%) and 5-methylene-2,3,4,4-tetramethylcyclopenten-2-enone (10.97%) were the major compounds in essential oil from dormancy stage, while the main compounds in flowering stage were trans-α-necrodyl acetate (26.90%), trans-α-necrodol (13.02%), lavandulyl acetate (6.53%) and linalool (5.82%). A strong antifungal activity of the essential oils was found against all strains, with MIC and MFC values ranged from 0.07-0.29 µL/mL and 0.58-9.33 µL/mL, respectively.
- Essential oils of two portuguese endemic species of lavandula as a source of antifungal and antibacterial agentsPublication . Domingues, Joana Lopes; Goulão, Manuela; Delgado, F.M.G.; Gonçalves, José Carlos; Gonçalves, Joana; Pintado, Cristina SantosChemical investigations of L. stoechas subsp. luisieri and L. pedunculata essential oils were analyzed by GC-MS, and the antimicrobial activity was performed against bacteria and fungi isolated from food sources. The cytotoxicity of the essential oil was performed in NHDF cells using the MTT method. According to the results, the main compounds of L. stoechas subsp. luisieri essential oil were trans-α-necrodyl acetate (40.2%), lavandulyl acetate (11%), and trans-α-necrodol (10.4%), while fenchone (50.5%) and camphor (30.0%) in L. pedunculata essential oil. The antifungal activity of essential oils was confirmed with MIC values ranging from 1.2 to 18.7 µL/mL; for bacteria, it ranged from 4.7 to 149.3 µL/mL. Both the Lavandula species tested showed low or equal MIC and MBC/MFC values for L. stoechas subsp. luisieri essential oil, revealing greater efficacy in antimicrobial activity. The L. stoechas subsp. luisieri essential oil revealed cytotoxic effects (30 ± 2% of cell viability) in NHDF cells at all concentrations tested.
- A global review of cheese colour: microbial discolouration and innovation opportunitiesPublication . Ferraz, Ana Rita Simões; Pintado, Cristina Santos; Serralheiro, Maria LuísaCheese is a biologically active food product, characterised by its colour, texture, and taste. Due to its rich matrix of fats and proteins, as well as the fact that the cheese’s surface acts as its own packaging, the cheese becomes more susceptible to contamination by microorganisms during the ripening process, particularly bacteria and fungi. The ripening of cheese involves several biochemical reactions, with the proteolytic activity of the cheese microbiota being particularly significant. Proteolysis results in the presence of free amino acids, which are precursors to various metabolic mechanisms that can cause discolouration (blue, pink, and brown) on the cheese rind. Surface defects in cheese have been documented in the literature for many years. Sporadic inconsistencies in cheese appearance can lead to product degradation and economic losses for producers. Over the past few decades, various defects have been reported in different types of cheese worldwide. This issue also presents opportunities for innovation and development in edible and bioactive coatings to prevent the appearance of colour defects. Therefore, this review provides a comprehensive analysis of cheese colour globally, identifying defects caused by microorganisms. It also explores strategies and innovation opportunities in the cheese industry to enhance the value of the final product.
- High seroprevalence of Brucella spp. in wild boar and red deer in the Centre of PortugalPublication . Pires, Humberto; Matos, Manuela; Cardoso, Luís; Lopes, Ana Patrícia; Fontes, Maria da Conceição; Pintado, Cristina Santos; Figueira, Luís; Matos, Ana Cristina; Mesquita, João Rodrigo; Coelho, Ana CláudiaHigh seroprevalence of Brucella spp. in wild boar and red deer in the Centre of Portugal.
- Hunting for answers: Assessing Brucella spp. seroprevalence and risks in red deer and wild boar in Central PortugalPublication . Pires, Humberto; Cardoso, Luís; Lopes, Ana Patrícia; Fontes, Maria da Conceição; Silva, Sérgio Santos; Matos, Manuela; Pintado, Cristina Santos; Roque, Natália; Fonseca, Leonardo Filipe; Morgado, Inês; Dias, Ana Sofia; Figueira, Luis; Matos, Ana Cristina; Mesquita, João Rodrigo; Coelho, Ana CláudiaBetween 2016 and 2023, a cross-sectional study was conducted in the central region of Portugal in order to better understand the epidemiology and public health risks resulting from the handling and consumption of game animals infected with Brucella spp. The seroprevalence and risk factors for Brucella spp. seropositivity were evaluated. Antibodies against Brucella spp. were determined using a commercial enzyme-linked immunosorbent assay (ELISA) according to the manufacturer’s instructions. Results showed that in the 650 serum samples collected from red deer (n = 298) and wild boars (n = 352) in Portugal, 21.7% (n = 141; 95% CI: 18.6–25.1%) tested positive. Wild boar had a significantly higher prevalence (35.5%; 95% CI: 30.5–40.8%) than red deer (5.4%, 95% CI: 3.1–8.6%; p ≤ 0.001). Risk factors for seropositivity were investigated using multivariable logistic regression models. The odds of being seropositive was 8.39 (95% CI: 4.75–14.84; p ≤ 0.001) times higher in wild boar than in red deer. Correlations between sex, age, body condition, and seropositivity could not be observed. The higher seroprevalence in wild boar suggests that this species may primarily contribute to the Brucella spp. ecology in central Portugal
- Implementação da técnica AFLP (Amplified Fragment Length Polymorphisms) para a tipagem molecular de Listeria spp.Publication . Leitão, Ana Maria; Reis, C.M.G.; Pedroso, Ana Sofia; Dinis, Patrícia; Pintado, Cristina SantosCom este trabalho foi possível implementar na ESACB a técnica de biologia molecular Amplified Fragment Length Polymorphisms (AFLP), com vista à tipagem molecular de culturas de Listeria monocytogenes e outras Listeria spp., as quais tinham sido isoladas maioritariamente de queijo, leite cru e ambiente de uma queijaria. A técnica apresentou uma boa reprodutibilidade e poder discriminatório para Listeria monocytogenes e L. innocua. Relativamente à espécie L. ivanovii, obtiveram-se perfis com um reduzido número de bandas. Verificou-se a presença de uma banda com aproximadamente 850 pb, comum às amostras estudadas de L. monocytogenes e L. innocua.