Browsing by Author "Freitas, Ana C."
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- Analytical strategies for characterization and validation of functional dairy foodsPublication . Rodrigues, Dina; Rocha-Santos, Teresa A.P.; Freitas, Ana C.; Gomes, Ana M.P.; Duarte, Armando C.Functional foods (FFs) are food products to be consumed as part of a balanced diet. They provide physiological benefits or reduce the risk of chronic disease beyond basic nutritional functions. Functional foods containing probiotics and/or prebiotics have gained much interest in recent years due to their health-promoting capacity. The main objective of this review is to discuss the analytical strategies that have been used to validate FFs associated with dairy products containing probiotics and/or prebiotics. In these products, the biochemical events, carried out by enzymes of different sources (milk, bacteria, rennet) leading to the transformation of milk to diverse products (e.g., yoghurt and cheese), are glycolysis, proteolysis and lipolysis. We present the analytical methodologies used to study the microbial probiotic flora and to evaluate the biochemical transformations, the associated functionality in terms of intestinal microbiome and the safety of such FFs. We address the analytical figures of merit. We cover the advantages and the disadvantages of such analytical methodologies and comment on future applications and potential research interest within this field.
- 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.
- Antibacterial and antioxidant potential of aqueous extracts of bio-residues from agrocybe cylindracea and pleurotus ostreatus myceliumPublication . Sousa, Ana Sofia; Nunes, Catarina; Barros, Joana; Ferreira, Inês; Freitas, Ana C.; Morais, Alcina M. M. B.; Nunes, João; Pintado, ManuelaThe production of fresh mushrooms results in a large quantity of bio-residues, which may account for more than 20% of a crop volume and contributes to production costs and environmental impact, if not used. These products consist mainly of stalks, mushrooms of irregular dimensions and shape and basal material. Thus, the main objective of MicoBioExtract project is the valorisation of these bio-residues and the development of add-value by-products with bioactive compounds such as polysaccharides and phenolic compounds produced by mushrooms. In the present work, the aqueous extracts from Agrocybe cylindracea byproducts (ACB) and Pleurotus ostreatus mycelium (POM) were evaluated for potential antioxidant and antimicrobial activities. Water soluble substances were extracted from mushrooms according to two different methods. In method 1 it was performed a hot extraction (extract 1A; 90 °C; 1 h; 500 rpms). In method 2, the biomass was submitted to an extraction at room temperature (extract 2B) and the resulting residue was extracted with hot water (extract 2C; 90 °C; 1 h; 500 rpms). The aqueous extracts from POM were obtained only by method 1. Extracts were lyophilized and their bioactivity evaluated measuring the antioxidant (ABTS, DPPH and ORAC) and antimicrobial (determination of the minimum inhibitory concentration – MIC) activities. The mutagenicity was also tested (Ames assay with and without S9). Moreover, it was determined the total phenolics content of the extracts and α and β – glucans (Folin Ciocalteu and Beta-Glucan Assay methods, respectively). The results obtained from antioxidant methods showed that all extracts from both mushrooms are a potential source of natural antioxidant and phenolic compounds. According to ABTS, extract 2B from ACB showed the best value with 8.48±0.33 mg ascorbic acid equivalent (AAE)/g dry extract and 4.14±0.52 mg AAE/g dry extract for POM. Regarding the antimicrobial activity, MIC results showed that ACB and POM extracts inhibited the growth of Gram- (Salmonella enteritidis) and Gram+ (Bacillus cereus and Listeria monocytogenes). Concerning the mutagenicity, the results showed no toxic effect except for extract 1A from ACB. Regarding the β-glucan content, the extracts from ACB presented higher content of β-glucan than the C extracts from POM. Thus, aqueous extracts from mushroom bio-residues showed potential antioxidant and antimicrobial properties and to develop a circular bioeconomy approach.
- 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.
- Can growth of nannochloropsis oculata under modulated stress enhance its lipid-associated biological properties?Publication . Sousa, Sérgio C.; Machado, Manuela; Freitas, Ana C.; Gomes, Ana M.; Carvalho, Ana P.Nannochloropsis oculata is well-recognized as a potential microalgal source of valuable compounds such as polyunsaturated fatty acids, particularly, eicosapentaenoic acid (EPA). The content and profile of these lipids is highly dependent on the growth conditions and can, therefore, be tailored through modulation of the growth parameters, specifically, temperature. Moreover, biological activities are composition dependent. In the present work, lipid extracts obtained from N. oculata, grown under constant temperature and under modulated temperature stress (to increase EPA content; Str) were characterized by GC-FID and several bioactivities were evaluated, namely, antioxidant (L-ORACFL), cytotoxic (MTT), adipolytic, anti-hepatic lipid accumulation (steatosis), and anti-inflammatory properties. Both extracts exhibited antioxidant activity (c.a. 49 µmol Troloxequivalent/mgextract) and the absence of toxicity (up to 800 µg/mL) toward colon and hepatic cells, adipocytes, and macrophages. They also induced adipolysis and the inhibition of triglycerides hepatic accumulation, with a higher impact from Str. In addition, anti-inflammatory activity was observed in the lipopolysaccharide-induced inflammation of macrophages in the presence of either extract, since lower levels of pro-inflammatory interleukin-6 and interferon-β were obtained, specifically by Str. The results presented herein revealed that modulated temperature stress may enhance the health effects of N. oculata lipid extracts, which may be safely utilized to formulate novel food products.
- Challenges in functional foods development based on bioactive lipidsPublication . Machado, Manuela; Freitas, Ana C.; Pintado, Manuela; Gomes, Ana MariaLipids have an important role in human health. Their health benefits include the reduction of cardiovascular diseases, the improvement of cognitive function, and they act as antiinflammatory and antioxidant compounds. Despite these benefits, the consumption of these compounds is very low, due to the actual lifestyles and lack of knowledge by the general consumer. On the other hand, during food production and storage, the total amount of lipids decreases due to the oxidative processes. For this reason, many strategies have been developed to control the oxidation processes and their consequences and enhancing the amount of these bioactive compounds in foods. In this chapter, the principal challenges in functional foods developed are reviewed focusing on the oxidation processes. The encapsulation techniques and the addition of antioxidants are also addressed as the main strategies to solve the oxidation consequences.
- 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.