Browsing by Author "Morais, Rui M. S. C."
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- Alginate: Pharmaceutical and Medical ApplicationsPublication . Batista, Patrícia; Morais, Alcina M. M. B.; Pintado, Maria Manuela; Morais, Rui M. S. C.Due to their outstanding properties in terms of mild gelation conditions and simple functionalization, biocompatibility, low toxicity, biodegradability, non-antigenicity and chelating ability, as well as relatively low cost, alginates have been widely used in a variety of biomedical applications including tissue engineering and drug delivery systems. Smart alginate hydrogels for on-demand drug release in response to environmental stimuli and 3D bioprinting will play an important role in the future. These and the introduction of appropriate cell interactive features will be crucial for many tissue engineering applications. The focus of the present chapter is to highlight the great potential of the alginates as biomaterial for biomedical applications and to discuss the role that alginate-based materials are likely to play in biomedical applications in the future.
- Bioactive profile, bioaccessibility and antioxidant activity of diatoms: a comparative studyPublication . Rocha, Helena R.; Coelho, Marta; Coelho, Natacha; Morais, Rui M. S. C.; Pintado, Manuela E.; Gomes, Ana M.Diatoms are microalgae with significant biotechnological potential due to their richness in bioactive compounds, including carotenoids and phenolics, contributing to their antioxidant properties. This study aims to compare the bioactive profile and antioxidant activity of three diatom species: Chaetoceros calcitrans, Nannofrustulum shiloi, and Cylindrotheca fusiformis cultivated in closed Flat Panel photobioreactors by Necton S.A. The biomass was harvested via centrifugation, freeze-dried, milled, and vacuum-packed for subsequent analysis.Carotenoids were extracted using ethanolic extraction assisted by ultrasound and analyzed through HPLC-DAD. The Total phenolic content (TPC) was determined using the Folin-Ciocalteu method, considering both free and bound phenolics to provide a comprehensive understanding of their distribution. Antioxidant activity was evaluated using ABTS, ORAC, and DPPH assays, offering complementary insights into the radical-scavenging potential of the diatom species. Additionally, a bioaccessibility assessment was performed using the standardized INFOGEST in vitro model to evaluate the stability of these bioactive compounds.Carotenoid analysis revealed distinct profiles among the species. N. shiloi exhibited the highest levels of β-carotene and zeaxanthin, highlighting its strong potential as a source of antioxidant pigments, whereas C. fusiformis showed a balanced composition of β-carotene, zeaxanthin, and other carotenoids, suggesting a varied antioxidant capacity. In contrast, C. calcitrans contained comparatively lower levels of these carotenoids. In addition to carotenoids, phenolic compounds play a significant role in the antioxidant potential of these diatoms. The TPC varied significantly, with C. fusiformis presenting the highest levels, followed by N. shiloi and C. calcitrans. Besides the differences in the results of the antioxidant activity among species, all exhibited considerable antioxidant capacity, suggesting the presence of multiple bioactive compounds contributing to distinct yet effective mechanisms of action.These findings highlight the potential of diatoms as sources of natural bioactives, particularly for nutraceutical and pharmaceutical applications. The study underscores the importance of species selection in maximizing bioactive compound yield and antioxidant properties, paving the way for further exploration in functional food and cosmetic industries.
- Biodegradable films with polysaccharides, proteins, and bioactive compounds from lobosphaera sp.: antioxidant and antimicrobial activitiesPublication . Martins, Valter F. R.; Lopes, Ana I.; Machado, Manuela; Costa, Eduardo M.; Ribeiro, Tânia B.; Poças, Fátima; Pintado, Manuela; Morais, Rui M. S. C.; Morais, Alcina M. M. B.Microalgae are a sustainable source of bioactive compounds and nutrients that do not compete with crops for arable land. Lobosphaera sp. was used to produce biodegradable films. Bioactive compounds, polysaccharides, and proteins were extracted from this microalga. The total phenolic content (TPC) and antioxidant activity (ABTS, DPPH, and ORAC) of the bioactive-rich extract were determined, and its composition was analyzed for phenolics using LC-ESI-QqTOF-HRMS and for lipids using GC-FID. The cytotoxicity of this extract on Caco-2 cells was also assessed. Different types of films were produced based on alginate (2%) (film A) and alginate with polysaccharides-rich (PS-rich) extract (0.5%) (film B); PS-rich extract and bioactive-rich extract (0.25%) (film C); protein-rich (P-rich) extract (0.5%) (film D); and P-rich extract and bioactive-rich extract (film E). The antioxidant activity and physical parameters of the films, such as thickness, color, water vapor permeability, solubility, tensile strength (TS), and elongation at break (EAB), were determined. The TPC of the bioactive-rich extract was 1.07 ± 0.05 mg GAE/100 mg DW, and its antioxidant activity was 2.44 ± 0.27, 1.67 ± 0.15, and 11.90 ± 1.22 µmol TE/100 mg DW for ABTS, DPPH, and ORAC, respectively. The extract showed no cytotoxicity to gut cells at concentrations equal to or below 1.0 mg/mL. Film E obtained the best results for the antioxidant activity, 451.06 ± 14.68 and 212.81 ± 39.12 µM TE/mg film for ABTS and DPPH, respectively. In addition, the films enriched with the bioactive-rich extract (films C and E) presented antimicrobial activity against Listeria monocytogenes. These films controlled the mold and yeast growth in strawberries during a four-day storage at 25 °C. All films were completely soluble in water and hydroethanolic solutions but only partially solubilized in acetic acid (3%). TS and EAB were not significantly different among the films. It was possible to produce biodegradable films using microalga Lobosphaera sp. with good bioactivity and physical characteristics.
- Biostimulant effect of two fucus sp. algal residues on pea, rice, and tomato germination and growthPublication . Sperotto, Raul A.; Rosa-Martínez, Elena; Martins, Valter F. R.; Pintado, Manuela; Morais, Rui M. S. C.; Morais, Alcina M. M. B.; Vasconcelos, Marta W.Introduction: Seaweed-based bioproducts are increasingly recognized for their phytostimulatory properties, promoting plant growth and enhancing resistance to various stresses. Notably, Fucus vesiculosus, a brown seaweed, has shown promise as a biostimulant1. Exopolysaccharides (EPSs) constitute different classes of organic macromolecules that can have multiple applications. This study investigates the bioestimulant effects of Fucus sp. on the germination and early growth of pea, rice, and tomato, utilizing two algal extracts—one with EPS and another without EPS. The goal was to assess the impact of the algal residues on seed germination and initial plant development and provide insights into their potential as sustainable biostimulants. Conclusions: The three crops responded differently to applying algae extracts in the substrate as a biostimulant. The most promising results were obtained for rice and tomato since they showed a biostimulating effect on crop growth in the early stages of development, which was demonstrated mainly in the significant increase in plant dry biomass. Ultimately, the algae residue without EPS (BS-EPS at both concentrations) gave better results than the algae residue with EPS, as it significantly promoted the development of rice and tomato seedlings.
- A comparative study of drying technologies for apple and ginger pomace: kinetic modeling and antioxidant propertiesPublication . Araujo, Beatriz Z. R.; Martins, Valter F. R.; Pintado, Manuela E.; Morais, Rui M. S. C.; Morais, Alcina M. M. B.Apple and ginger mixed pomace is a by-product that can be valorized by drying. In this study, mixed pomace was subjected to hot-air drying (HAD) at 45, 62, and 70 °C and stepwise at 45 °C followed by at 62 °C or the reverse, at 62 °C followed by at 45 °C (2.5 mm layer), and microwave drying (MWD) at 100, 180, and 300 W (2.5 mm and 1.5 mm layers) and stepwise at 100 W followed by at 3000 W (2.5 mm layer). The results show that the Crank model well fitted the HAD kinetics, with a water effective diffusivity (Deff) of 2.28 ± 0.06 × 10−10–4.83 ± 0.16 × 10−10 m2/s and energy of activation of 23.9 kJ/mol. The step approach of drying at 45 °C followed by at 62 °C resulted in a higher Deff than the reverse approach (drying at 62 °C followed by at 45 °C). The Midilli et al. model presented a good fit for the MWD kinetics. The drying time was calculated using these models to achieve 12% moisture content in the pomace and found to be 125.0 ± 9.2–439.5 ± 118.2 min for HAD, and 11.1 ± 0.2–61.5 ± 6.0 min for MWD. The specific energy required was 410.78 ± 6.30–763.79 ± 205.4 kWh/kg and 1.32 ± 0.01–2.26 ± 0.05 kWh/kg, respectively. MWD at 180 W preserved the total phenolic content and the antioxidant activity (ABTS, DPPH) better than HAD at 62 °C. The former technology also preserved the pomace color well, with a low color difference, ΔE, of 7.39 ± 1.1. Therefore, MWD is more promising than HAD to dry apple and ginger pomace, reducing the environmental impact of the drying process due to its lower energy consumption, shorter drying time, and better quality. The dried product could be converted into apple and ginger pomace flour to be used as a novel food ingredient.
- Comparison among different green extraction methods of polyphenolic compounds from exhausted olive oil pomace and the bioactivity of the extractsPublication . Martins, Valter F. R.; Ribeiro, Tânia B.; Lopes, Ana I.; Pintado, Manuela E.; Morais, Rui M. S. C.; Morais, Alcina M. M. B.The use of by-products as a source of bioactive compounds with economic added value is one of the objectives of a circular economy. The olive oil industry is a source of olive pomace as a by-product. The olive pomace used in the present study was the exhausted olive pomace, which is the by-product generated from the air drying and subsequent hexane extraction of residual oil from the olive pomace. The objective was to extract bioactive compounds remaining in this by-product. Various types of green extraction were used in the present study: solvent extraction (water and hydroalcoholic); ultrasound-assisted extraction; Ultra-Turrax-assisted extraction; and enzyme-assisted extraction (cellulase; viscoenzyme). The phenolic profile of each extract was determined using HPLC-DAD and the total phenolic content (TPC) and antioxidant activity (ABTS, DPPH, and ORAC) were determined as well. The results showed significant differences in the yield of extraction among the different methods used, with the enzyme-assisted, with or without ultrasound, extraction presenting the highest values. The ultrasound-assisted hydroethanolic extraction (USAHE) was the method that resulted in the highest content of the identified phenolic compounds: 2.021 ± 0.29 mg hydroxytyrosol/100 mg extract, 0.987 ± 0.09 mg tyrosol/100 mg extract, and 0.121 ± 0.005 mg catechol/100 mg extract. The conventional extraction with water at 50 °C produced the best results for TPC and antioxidant activity of the extracts. The extracts from the USAHE were able to inhibit Gram-positive bacteria, especially Bacillus cereus, showing 67.2% inhibition at 3% extract concentration.
- Conservação do espargo-do-mar em atmosfera controladaPublication . Raposo, M. Filomena J.; Morais, Rui M. S. C.; Morais, Alcina M. M. B.A salicórnia mais conhecida por espargo-do-mar, pode ser utilizada como delicatessen ou alimento gourmet, em saladas, como pickles,e, ainda, para aromatizar azeite. A atmosfera controlada parece ser uma boa tecnologia para conservar as características bioquímicas e organolépticas dos rebentos de salicórnia.
- Desidratação osmótica de cubos de maçã e fisális com soluções de sorbitolPublication . Assis, Fernanda R.; Morais, Rui M. S. C.; Morais, Alcina M. M. B.Este trabalho teve como objetivo estudar a utilização potencial do sorbitol como agente no processo de desidratação osmótica (DO). Além de apresentar baixas calorias e ser menos doce e menos cariogénico que a sacarose, o sorbitol é um prebiótico com propriedades de saúde comprovados. Cubos de maçã foram desidratados osmoticamente a temperaturas entre 25 e 60 ºC, utilizando solução de sacarose ou sorbitol a 60 ºBrix e razão mássica de fruto/solução de 1:4 ou 1:10, sob pressão atmosférica ou vácuo de 150 mbar. A DO de fisális foi realizada nas condições otimizadas da DO de cubos de maçã (60 ºC, 1:4), relativamente às cinéticas de perda de água (PA). A utilização do sorbitol como agente osmótico resultou num aumento das cinéticas, a ambas as pressões, pelo que é uma boa alternativa para substituir a sacarose. A razão de 1:4 é também uma melhor opção que a razão de 1:10. A utilização de vácuo na DO de maçãs não produziu diferenças significativas, mas revelou tendência para aumentar a velocidade inicial de PA. À pressão atmosférica, a fisális apresentou o mesmo comportamento dos cubos de maçã. Porém, a vácuo, não se notou diferença entre as cinéticas dos solutos. A modelagem matemática das cinéticas de PA e ganho de soluto (GS) foi efetuada. Em geral, os modelos de Azuara, Peleg, Page e Weibull ajustaram-se bem aos dados experimentais; porém, o modelo de Penetração apresentou reduzida capacidade de ajuste.
- Edible films with protein and bioactive compounds from arthrospira sp.Publication . Martins, Valter F. R.; Poças, Fátima; Pintado, Manuela; Morais, Rui M. S. C.; Morais, Alcina M. M. B.Arthrospira sp. is an alternative source of protein in the food chain, but it may also be considered a source of phenolic compounds with interesting properties, such as antioxidant and antimicrobial properties. In active packaging, these two properties are essential. In the present work, two extracts were produced: one extract rich in protein and another in bioactives. These two extracts were used in the production of an edible film composed of alginate (2%) + protein extract (0.5%) + bioactive extract (0.25%) with high antioxidant activity: ABTS of 1537.50 ± 191.87 and DPPH of 190.75 ± 15.53 µM TE/mg film. All the edible films produced had good physical properties, such as 100% solubility in water and ethanolic solutions. The films with alginate and protein-rich extract and or without bioactive-rich extract presented lower water vapor permeability—12.28 ± 3.01 g⋅mm−2⋅day−1⋅kPa−1 and 14.39 ± 3.64 g⋅mm⋅m−2⋅day−1⋅kPa−1, respectively—than the alginate film. In addition, the film with alginate- and protein-rich extract presented an acceptable color.
- Effects of spray-drying and storage on astaxanthin content of Haematococcus pluvialis biomassPublication . Raposo, Maria Filomena J.; Morais, Alcina M. M. B.; Morais, Rui M. S. C.The main objective of this study was to evaluate the stability of astaxanthin after drying and storage at different conditions during a 9-week period. Recovery of astaxanthin was evaluated by extracting pigments from the dried powders and analysing extracts by HPLC. The powders obtained were stored under different conditions of temperature and oxygen level and the effects on the degradation of astaxanthin were examined. Under the experimental conditions conducted in this study, the drying temperature that yielded the highest content of astaxanthin was 220°C, as the inlet, and 120°C, as the outlet temperature of the drying chamber. The best results were obtained for biomass dried at 180/110°C and stored at −21°C under nitrogen, with astaxanthin degradation lower than 10% after 9 weeks of storage. A reasonable preservation of astaxanthin can be achieved by conditions 180/80°C, −21°C nitrogen, 180/110°C, 21°C nitrogen, and 220/80°C, 21°C vacuum: the ratio of astaxanthin degradation is equal or inferior to 40%. In order to prevent astaxanthin degradation of Haematococcus pluvialis biomass, it is recommended the storage of the spray dried carotenized cells (180/110ºC) under nitrogen and −21°C.
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