Browsing by Author "Pintado, M."
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- Alga Fucus sp. extracts to produce edible filmsPublication . Martins, V.; Machado, M.; Costa, E.; Gomes, A. M.; Poças, F.; Pintado, M.; Morais, R. M. S. C.; Morais, A. M. M. B.Introduction: Macroalgae are a good source of nutrients, such as carbohydrates (dietary fiber and polysaccharides), proteins, lipids and minerals [1,2]. Fucus sp. is composed of valuable bioactive compounds, such as fucoxanthin, vitamins, water-soluble (vitamin C and of complex B) and fat-soluble (vitamins A, D, E and K), phenolic compounds, lipids (MUFA and PUFA), and polysaccharides (fucoidans and alginic acid) [1]. This brown alga has been associated with health benefits, such as antioxidant, antimicrobial, anti-tumoral and anti-cancer properties [2]. Its application in the production of edible films presents high potential in food packaging, extending the shelf life of food products. Objectives: To evaluate the antioxidant activity and cytotoxicity bioactive extracts from Fucus sp. To produce an edible film based on PS enriched with the bioactive extracts. To test the antioxidant activity of the edible film. To test physico-chemical properties of the edible film, such as the color, thickness, solubility and water vapor permeability. Conclusions: Extraction at 300 W during 20 minutes is recommended for highest TPC and AA of the liquid extract. This extract showed no cytotoxicity for cells line HaCat. The edible film based on the PS extracted from Fucus sp. enriched with bioactives extracted also from this alga shows antioxidant activity, presents a high water vapor permeability, and 100 % solubility in water, which simulates hydrophilic foods, and lower solubility in hydroalcoholic solutions, which simulate hydrophobic foods. It has a brown color, characterized by relatively low luminosity and saturation values. This edible film has potential to be used in food packaging, whereas presenting high biodegradability.
- Antibacterial and antioxidant potential of aqueous extracts of bio-residues from agrocybe cylindracea and pleurotus ostreatus myceliumPublication . Sousa, A. S.; Marçal, S.; Costa, C.; Ferreira, I.; Barros, J.; Nunes, J.; Freitas, A. C.; Morais, A. M. M. B.; Pintado, M.The 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.
- Antihypertensive effect of spent brewer yeast peptidePublication . Amorim, M.; Marques, C.; Pereira, J. O.; Guardão, L.; Martins, M. J.; Osório, H.; Moura, D.; Calhau, C.; Pinheiro, H.; Pintado, M.Numerous studies have investigated dietary approaches to prevent chronic lifestyle-related diseases, including hypertension. Spent brewer's yeast is the second largest byproduct originated by the brewing industry and it deserves considerable attention because of its high nutritional value, ca. 40% of its dry mass is rich in protein which can be hydrolyzed into biologically active peptides. To upgrade this byproduct, the aim of this study was initially in vitro assessment of biological properties, e.g. ACE inhibition and antioxidant activity, and then, the in vivo effect in short-term oral antihypertensive effect of hydrolyzed yeast fractions on a well characterized model to study hypertension - Spontaneously Hypertensive Rats (SHR). Here, it was demonstrated that the fraction with molecular weight below 3 kDa containing tri and tetra- peptides with hydrophobic amino acid residues - SPQW, PWW and RYW, causes the most noticeable decrease in systolic, diastolic and mean blood pressure of SHR and shows highest antioxidant effect. These properties highlight the potential use of yeast extract as nutraceutical or functional food ingredient for the management and treatment of hypertension with antioxidant effect.
- Antimicrobial activity of organic acids against some common food spoilage and pathogenic microorganismsPublication . Sorathiya, K.; Melo, A.; Rodrigues, C.; Paulico, L.; Barracosa, R.; Correia, D.; Pintado, M.Background: In recent years, the food industry is challenged to produce high-quality products using natural preservative alternatives instead of synthetic ones, owing to the increasing consumer demand for clean-label food products. Organic acids have potential as an alternative due to their antimicrobial activity and high food safety (GRAS). Therefore, the objective of this work was to investigate the antimicrobial activity of organic acids against some common food spoilage and pathogenic microorganisms for use in food formulation. Method: The antimicrobial activity of the organic acids (lactic, citric, and propionic acid) was tested at different concentrations ranging from 0.06 to 4% by microdilution method in 96 well plates against Lactobacillus plantarum, Escherichia coli; Candida intermedia, Pichia fermentans, Penicillium glabrum, and Aspergillus niger. The minimum inhibitory concentration (MIC) was recorded as the lowest concentration at which complete inhibition of visible growth occurred. Results: The MICs of lactic, citric, and propionic acid for E. coli were 0.25, 0.25, and 0.125% respectively, while for L. plantarum, they were 0.25, 0.25, and 0.06% respectively. Regarding the yeasts, the MIC of lactic, citric, and propionic acid for C. intermedia were 1, 2, and 0.125%, respectively and for P. fermentans they were 1, 0.5, and 0.5%, respectively. Propionic acid also shows fungicidal potential against A. niger and P. glabrum with MIC values 0.5 and 0.25, respectively. Lactic acid displayed a MIC value of 4% representing the highest MIC value observed for both, while citric acid did not inhibit these fungi. Conclusion: The organic acids tested showed significant antimicrobial potential at low concentrations, particularly lactic and propionic acids. Future studies will incorporate the most promising acids as substitutes for synthetic preservatives to verify their ability to maintain antimicrobial effectiveness over time when incorporated into foods.
- Antimicrobial activity of phenolic compounds identified in wild mushrooms, SAR analysis and docking studiesPublication . Alves, M. J.; Ferreira, I. C. F. R.; Froufe, H. J. C.; Abreu, Rui M. V.; Martins, A.; Pintado, M.Aim and Methods: Although the antimicrobial activity of extracts from several mushroom species has been reported, studies with the individual compounds present in that extracts are scarce. Herein, the antimicrobial activity of different phenolic compounds identified and quantified in mushroom species from all over the world was evaluated. Furthermore, a structure-activity relationship (SAR) analysis and molecular docking studies were performed, in order to provide insights into the mechanism of action of potential antimicrobial drugs for resistant micro-organisms. Results: 2,4-Dihydroxybenzoic and protocatechuic acids were the phenolic compounds with higher activity against the majority of Gram-negative and Gram-positive bacteria. Furthermore, phenolic compounds inhibited more MRSA than methicillin-susceptible Staphylococcus aureus. MRSA was inhibited by 2,4-dihydroxybenzoic, vanillic, syringic (MICs = 0.5 mg ml(-1)) and p-coumaric (MIC = 1 mg ml(-1)) acids, while these compounds at the same concentrations had no inhibitory effects against methicillin-susceptible Staph. aureus. Conclusions: The presence of carboxylic acid (COOH), two hydroxyl (OH) groups in para and ortho positions of the benzene ring and also a methoxyl (OCH3) group in the meta position seems to be important for anti-MRSA activity. Significance and Impact of the Study: Phenolic compounds could be used as antimicrobial agents, namely against some micro-organisms resistant to commercial antibiotics.
- Antimicrobial activity of potential essential oils to replace potassium sorbate in fruit preparationsPublication . Melo, A.; Sorathiya, K.; Rodrigues, C.; Paulico, L.; Barracosa, R.; Pintado, M.Introduction: In recent years, the food industry has faced the challenge of producing high-quality products using natural preservative alternatives instead of synthetic ones. Essential oils (EO), naturally present in various plants, have potential as alternatives due to their antimicrobial activity and high food safety (Generally Recognized as Safe, GRAS). This study aimed to investigate the antimicrobial activity of EO against common spoilage and pathogenic microorganisms in fruit preparations, to use as a substitute for potassium sorbate (PS). Methodology: The antimicrobial activity of lemongrass and lemon EO was tested using the microdilution method in 96-well plates against Lactobacillus plantarum, Escherichia coli; Candida intermedia, Pichia fermentans, Aspergillus niger and Penicillium glabrum.EO were tested at concentrations ranging from 1.56 to 50% and PS at 0.03 to 4%. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. Results: The MICs of lemongrass and lemon EO for E. coli were 3.12 and 12.5%, respectively, while for L. plantarum, they were 1,56 and 6.25% respectively. Regarding the yeasts, the MIC of lemongrass and lemon EO for C. intermedia were 1.56 and 3.12%, respectively, and for P. fermentans, they were 1.56 and 1.56%, respectively. Lemongrass EO showed the same MICs value of 6.25% against A. niger, and P. glabrum. Lemon EO also displayed the same MICs values of 25% for A. niger, and P. glabrum representing the highest MICs values observed. The MBCs values was similar the MICs values to all microorganisms except to L. plantarum that were 6.25 and 25% to lemongrass and lemon EO, respectively. PS showed MICs values of 1 and 2% for E. coli and L. plantarum, respectively, with MBCs values of 2% for both. For yeasts, the MIC was 0.06% for both with MBC values of 0.06% for E. coli and 0.5% for L. plantarum. The MIC and MBC values were the same of 0.06% for both fungi. Conclusion: The EO tested showed significant antimicrobial potential at low concentrations, particularly lemongrass EO. Future studies will incorporate this oil as substitutes for PS to verify their ability to maintain antimicrobial effectiveness over time when incorporated in fruit preparations.
- Antioxidant peptides obtained from enzymatic hydrolysis of animal by-productsPublication . Borges, S.; Odila, J.; Voss, G.; Martins, R.; Rosa, A.; Vanderpoorten, W.; Almeida, A.; Pintado, M.
- Apparent digestibility coefficients of processed agro-food by-products in European seabass (Dicentrarchus labrax) juvenilesPublication . Campos, I.; Matos, E.; Aragão, C.; Pintado, M.; Valente, L. M. P.Apparent digestibility coefficients (ADCs) of processed agro-food by-products were assessed in European seabass Dicentrarchus labrax). Each experimental diet was obtained by replacing 300 g/kg of a commercial-based diet used as reference (REF) with a test ingredient: wheat germ (GERM), okara meal (OKA), poultry by-product meal (POULT), steam hydrolysed (FeHY) and enzyme-treated feather meal (FeENZ), beta-lactoglobulin (β-Lg) and peptide fractions >3,000 Da obtained from brewer’s yeast (YeastP) and fish by-products (FishP). Dry matter ADC was highest in β-Lg (95%) and lowest in OKA (40%). Protein ADCs were high in β-Lg, FishP, GERM and POULT (>93%); intermediate in FeHY and FeENZ (85%–88%); and moderate in OKA and YeastP (70%–78%). The essential amino acids’ ADC mean was above 91% in POULT, β-Lg, GERM and FishP, 84%–89% in FeHY and FeENZ and 73%–76% in YeastP and OKA. Energy ADC was highest in POULT and β-Lg (89%–95%) and lowest in YeastP and OKA (61%–64%). Lipid ADC was highest for POULT and GERM (100%). Phosphorus ADC was lowest in GERM (19%) and highest in β-Lg (88%). FeHY, FeENZ, POULT, GERM, FishP and β-Lg are highlighted as protein sources for European seabass.
- Attempts in enzymatic degradation of the pigmentation produced by fungi isolated from Portuguese wall paintingsPublication . Marco, A.; Moreira, P. R.; Pintado, M.; Vieira, E.Wall paintings are prone to different types of deterioration, including of biological origin. Our study focuses on the chromatic alterations of the paintings’ surfaces related to the presence and growth of microorganisms. The removal of the dark coloured stains from wall paintings is extremely difficult. Although treatment with biocides can eliminate microorganisms, these compounds are ineffective in cleaning the black pigmentation resulting of their growth. Therefore, it is necessary to understand which organisms are present, the characteristics of the compounds they generate, and in which conditions they produce it. The aim of this study was to isolate the pigment that is the source of the black stains in the studied wall paintings in order to, in a broader scope, eliminate or attenuate their visual impact. Wall paintings presenting black stains from three case studies – Igreja de Santa Eulália/Igreja de São Salvador de Arnoso (V.N. Famalicão), Igreja Paroquial de Valadares (Baião) and Igreja de Santa Cristina de Serzedelo (Guimarães) were dully studied from the conservation point of view. Fungi were isolated from selected areas that displayed dark pigmentation of the pictorial layer. Samples were collected with wet swabs and grown on solid culture medium, e.g. Potato Dextrose Agar (PDA). Isolates were further identified by classical and molecular biology methodologies. Three fungal isolates were selected for further studies due to their pigmentation and growth characteristics, mainly: blackening of solid culture media, dark or black hyphae growth, or a presence of black exudates produced by colourless hyphae. Enzymatic degradation of pigmentation resulting from a selected fungal isolates was attempted both in solution and on solid support and tested with fungal versatile peroxidase from Bjerkandera adusta. Changes in colour were detected by UV-Vis spectrophotometry and with a CIE L*a*b system colorimeter.
- Auditing functional phytochemicals during fruit processingPublication . Oliveira, A.; Pintado, M.; Almeida, Domingos P. F.