Percorrer por autor "Rocha-Santos, Teresa A. P."
A mostrar 1 - 10 de 20
Resultados por página
Opções de ordenação
- Antibacterial activity of different water based seaweeds extracts against human pathogenic bacteriaPublication . Rodrigues, Dina; Pereira, Leonel; Rocha-Santos, Teresa A. P.; Freitas, Ana C.; Gomes, Ana; Duarte, Armando C.
- Bioactive polysaccharides extracts from sargassum muticumby high hydrostatic pressurePublication . Rodrigues, Dina; Freitas, Ana C.; Queirós, Rui; Rocha-Santos, Teresa A. P.; Saraiva, Jorge A.; Gomes, Ana M. P.; Duarte, Armando C.Sargassum muticum is an important source of bioactive polysaccharides; hence, high hydrostatic pressure (HHP) was used to improve their extraction efficiency. Response surface methodology and a Box-Behnken full factorial design were employed to assess and optimize the effects of extraction conditions on the yield, total sugars, total sulfated sugars and antioxidant activity of S. muticum extracts. The extraction yield ranged between 32 and 40.4% independently of the extraction conditions or seaweed solid/liquid ratio resulting in average increases of 3.6 to 4.8-fold for total sugars and sulfated sugars, as compared to conventional extraction. Extracts displayed improved antioxidant activities, yet maximum values were achieved under different optimum conditions of HHP processing, for example, 5–5.5 min, 300 MPa and 1 g of dry seaweed for yield. In conclusion, the optimal HHP technology conditions described in this paper enables to obtain enriched bioactive polysaccharide S. muticum extracts.
- Biodegradation of polyethylene microplastics by the marine fungus zalerion maritimumPublication . Paço, Ana; Duarte, Kátia; Costa, João P. da; Santos, Patrícia S.M.; Pereira, R.; Pereira, M. E.; Freitas, Ana C.; Duarte, Armando C.; Rocha-Santos, Teresa A. P.Plastic yearly production has surpassed the 300milliontons mark and recycling has all but failed in constituting a viable solution for the disposal of plastic waste. As these materials continue to accumulate in the environment, namely, in rivers and oceans, in the form of macro-, meso-, micro- and nanoplastics, it becomes of the utmost urgency to find new ways to curtail this environmental threat. Multiple efforts have been made to identify and isolate microorganisms capable of utilizing synthetic polymers and recent results point towards the viability of a solution for this problem based on the biodegradation of plastics resorting to selected microbial strains. Herein, the response of the fungus Zalerion maritimum to different times of exposition to polyethylene (PE) pellets, in a minimum growth medium, was evaluated, based on the quantified mass differences in both the fungus and the microplastic pellets used. Additionally, molecular changes were assessed through attenuated total reflectance Fourier transform Infrared Spectroscopy (FTIR-ATR) and Nuclear Magnetic Resonance (NMR). Results showed that, under the tested conditions, Z. maritimum is capable of utilizing PE, resulting in the decrease, in both mass and size, of the pellets. These results indicate that this naturally occurring fungus may actively contribute to the biodegradation of microplastics, requiring minimum nutrients.
- Characterization of freezing effect upon stability of, probiotic loaded, calcium-alginate microparticlesPublication . Sousa, Sérgio; Gomes, Ana M.; Pintado, Maria M.; Silva, José P.; Costa, Paulo; Amaral, Maria H.; Duarte, Armando C.; Rodrigues, Dina; Rocha-Santos, Teresa A. P.; Freitas, Ana C.Microencapsulation, utilizing different techniques and polymers, has been studied with the objective of maintaining probiotic viability in food matrices, protecting the cells from their detrimental environment, storage conditions andthe passage of gastrointestinal tract (GIT). The main objective of this study was to assess the effect of freezing at−20◦C upon probiotic alginate-calcium microparticles’ integrity and functionality through parameters such as size,morphology and structure of microparticles as well as to assess cell resistance to simulated gastrointestinal tractconditions upon storage. In order to study the effect of freezing upon the stability of the microparticles, calcium-alginate microparticles, with or without probiotic cells (Lactobacillus casei-01, Lactobacillus paracasei L26, Lactobacillusacidophilus KI and Bifidobacterium animalis BB-12), were characterized at production time and after 60 days storage at−20◦C. An increase in particle size, loss of the spherical shape and porous net damages were observed after 60 daysof storage at −20◦C. In accordance, encapsulation in alginate was not able to exert protection to the encapsulatedprobiotic cells stored at −20◦C for 60 days, especially from acid and particularly bile salts. B. animalis BB-12 revealedto be the most resistant probiotic strain, to both the microencapsulation process and to GIT simulated conditions.
- Chemical and structural characterization of Pholiota nameko extracts with biological propertiesPublication . Rodrigues, Dina; Freitas, Ana C.; Sousa, Sérgio; Amorim, Manuela; Vasconcelos, Marta W.; Costa, João P. da; Silva, Artur M. S.; Rocha-Santos, Teresa A. P.; Duarte, Armando C.; Gomes, Ana M. P.Edible mushrooms including Pholiota nameko are excellent sources of extractable bioactive compounds with much to explore. Enzymatic extractions with Cellulase and Viscozyme were responsible for highest extraction yields (67-77%). No strong antioxidant activity was observed although extracts were able to scavenge ABTS(+) and OH(+). Potential prebiotic activity was observed in all extracts, some increasing 1.4-2 Log cycles of Lactobacillus acidophilus La-5 and Bifidobacterium animalis BB12. 30-50% α-glucosidase inhibition was observed in ultrasound, Flavourzyme and Cellulase extracts. Flavourzyme and Cellulase extracts are richer in macro (Mg, K and P) and micro elements (Zn, Mn and Fe) in comparison to mushroom. Monosaccharides content and profile varied slightly among both extracts with predominance of glucose, galactose and mannose with no uronic acids detection; Flavourzyme extract reported higher free amino acids content. Presence of α and β-glycosidic structures such as glucans and glucan-protein complexes are among the polysaccharides found in both extracts.
- Chemical composition and nutritive value of Pleurotus citrinopileatus var cornucopiae, P. eryngii, P. salmoneo stramineus, Pholiota nameko and Hericium erinaceusPublication . Rodrigues, Dina M. F.; Freitas, Ana C.; Rocha-Santos, Teresa A. P.; Vasconcelos, Marta W.; Roriz, Mariana; Rodríguez-Alcalá, Luís M.; Gomes, Ana M. P.; Duarte, Armando C.The chemical composition and nutritive value of five mushrooms species, some less studied such as Pleurotus citrinopileatus var. cornucopiae, P. salmoneo stramineus or Pholiota nameko, were determined. Protein, sugar and fat contents ranged between 16.2 to 26.6, 52.7 to 64.9 and 2.3 to 3.5 g/100g(dry mushroom), respectively. Highest total phenolic content was observed for P. citrinopileatus var. cornucopiae with 1140 mu g cathecol equiv./g(dry mushroom). Higher content in mono and polyunsaturated fatty acids (FA) than saturated FA characterized mushrooms FA profile with high linoleic acid concentration (> 30 gFA/100g(fat)). In addition, these mushrooms may be considered good sources of K, Mg, P, highlighting K (2627-3736 mg/Kg(dry mushroom)) as the most predominant, and of Zn, Cu and Fe; some contributing over 15 % of their recommended daily intakes. beta-glucans, alpha-glucans and evidence of glucan-protein complexes were identified by FTIR-ATR. The reported values emphasize the nutritional potential of the five species to be consumed in a healthy diet.
- Chemical composition of red, brown and green macroalgae from Buarcos bay in Central West Coast of PortugalPublication . Rodrigues, Dina; Freitas, Ana C.; Pereira, Leonel; Rocha-Santos, Teresa A. P.; Vasconcelos, Marta W.; Roriz, Mariana; Rodríguez-Alcalá, Luís M.; Gomes, Ana M. P.; Duarte, Armando C.Six representative edible seaweeds from the Central West Portuguese Coast, including the less studied Osmundea pinnatifida, were harvested from Buarcos bay, Portugal and their chemical characterization determined. Protein content, total sugar and fat contents ranged between 14.4% and 23.8%, 32.4% and 49.3% and 0.6–3.6%. Highest total phenolic content was observed in Codium tomentosum followed by Sargassum muticum and O. pinnatifida. Fatty acid (FA) composition covered the branched chain C13ai to C22:5 n3 with variable content in n6 and n3 FA; low n6:n3 ratios were observed in O. pinnatifida, Grateloupia turuturu and C. tomentosum. Some seaweed species may be seen as good sources of Ca, K, Mg and Fe, corroborating their good nutritional value. According to FTIR-ATR spectra, G. turuturu was associated with carrageenan seaweed producers whereas Gracilaria gracilis and O. pinnatifida were mostly agar producers. In the brown algae, S. muticum and Saccorhiza polyschides, alginates and fucoidans were the main polysaccharides found.
- Disposable sensors for environmental monitoring of lead, cadmium and mercuryPublication . Duarte, Katia; Justino, Celine I. L.; Freitas, Ana C.; Gomes, Ana M. P.; Duarte, Armando; Rocha-Santos, Teresa A. P.Miniaturization is an increasing trend in the field of analytical chemistry as a response to the need to develop new analytical techniques for food, clinical, and environmental applications. There is therefore also an increasing trend towards the use of miniaturized disposable sensors, which are inexpensive and designed to be one-shot and do not require pre-treatment prior to use or cleaning between measurements. This review describes disposable sensors for detection of lead, cadmium and mercury in the environment, taking into account their analytical performance. Further, we also discuss the role of certain factors, such as the immobilization procedure and surface modification affecting the analytical characteristics of sensors. Finally, we comment on future applications and potential research interest in this field.
- Effect of probiotic co-cultures on physico-chemical and biochemical properties of small ruminants’ fermented milkPublication . Pinto, Jorge M. S.; Sousa, Sérgio; Rodrigues, Dina M.; Malcata, Francisco X.; Duarte, Armando C.; Rocha-Santos, Teresa A. P.; Freitas, Ana C.; Gomes, Ana M.Small ruminants' fermented probiotic milk is an alternative to fermented cows' milk, especially because of the monounsaturated/polyunsaturated fatty acid profiles. The technological and biochemical potential of Bifidobacterium and Lactobacillus co-cultures, with or without inulin, on goats' and ewes' milk was assessed. Microbial stability, lactose consumption, organic acid production, proteolytic parameters and conjugated linoleic acid (CLA) production in situ, were followed in ewes' and goats’ fermented milk (EFM and GFM, respectively) over 21 days at 4 °C; technological feasibility for probiotic fermented milk production was shown. In EFM, all co-cultures presented high viable cell numbers (>7.0 log cfu mL−1) throughout storage, presenting faster acidification capacities and higher CLA isomer levels than in GFM. Inulin had no impact on probiotic growth, yet contributed to storage stability. CLA isomers and proteolysis indices were co-culture dependent traits: for example, co-culture of Bifidobacterium animalis B94 with Lactobacillus acidophilus L10 registered the best CLA-production in GFM.
- Encapsulation of probiotic strains in plain or cysteine-supplemented alginate improves viability at storage below freezing temperaturesPublication . Sousa, Sérgio; Gomes, Ana M.; Pintado, Maria M.; Malcata, Francisco X.; Silva, José P.; Sousa, José M.; Costa, Paulo; Amaral, Maria H.; Rodrigues, Dina; Rocha-Santos, Teresa A. P.; Freitas, Ana C.Four probiotic bacteria (Lactobacillus paracasei L26, L. casei-01, L. acidophilus Ki, and Bifidobacterium animalis BB-12 R ) were encapsulated in plain alginate or alginate supplemented with L-cysteine·HCl, and resulting microcapsules were stored at different temperatures, namely 21, 4, −20, or −80◦C for a period of up to6months. The results showed that the encapsulation in calcium alginate microcapsules was only effective in promoting protection at freezing temperatures, independently of the sensitivity of the strain. Storage of calcium alginate microcapsules at −80◦C indicated a protective effect upon viability of all four probiotic strains and the presence of L-cysteine·HCl in the alginate matrix improved protection upon cell viability of B. animalis BB-12 R . An increase in storage temperature of encapsulated bacteria caused an increase in rate of loss in their viability that was strain dependent. This study suggests that microencapsulation of probiotic cells in calcium alginate can be suitable for sustaining the viability of probiotics in food products that require storage below freezing temperatures, even in the absence of cryoprotectors, contributing to an increased shelf life.