Browsing by Author "Abreu, Helena"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- Chemical composition and antioxidant potential of five algae cultivated in fully controlled closed systemsPublication . Nova, Paulo; Pimenta-Martins, Ana; Maricato, Élia; Nunes, Cláudia; Abreu, Helena; Coimbra, Manuel A.; Freitas, Ana Cristina; Gomes, Ana MariaIn this study, the chemical composition and antioxidant profile of five edible macroalgae, Fucus vesiculosus, Palmaria palmata, Porphyra dioica, Ulva rigida, and Gracilaria gracilis, cultivated in fully controlled closed systems, were determined. Protein, carbohydrates, and fat contents ranged between 12.4% and 41.8%, 27.6% and 42.0%, and 0.1% and 3.4%, respectively. The tested seaweeds presented considerable amounts of Ca, Mg, K, Mn, and Fe, which reinforce their favorable nutritional profile. Regarding their polysaccharide composition, Gracilaria gracilis and Porphyra dioica were rich in sugars common to agar-producing red algae, and Fucus vesiculosus was composed mainly of uronic acids, mannose, and fucose, characteristic of alginate and fucoidans, whereas rhamnose and uronic acid, characteristic of ulvans, predominated in Ulva rigida. Comparatively, the brown F. vesiculosus clearly stood out, presenting a high polysaccharide content rich in fucoidans, and higher total phenolic content and antioxidant scavenging activity, determined by DPPH and ABTS. The remarkable potential of these marine macroalgae makes them excellent ingredients for a wide range of health, food, and industrial applications.
- Determination of soluble and insoluble dietary fiber content of marine macroalgae and microalgaePublication . Nova, Paulo; Martins, Ana Pimenta; Silva, Joana Gabriela; Pereira, Rui; Abreu, Helena; Silva, Ana Machado; Freitas, Ana; Gomes, Ana
- Foods with microalgae and seaweeds fostering consumers health: a review on scientific and market innovationsPublication . Nova, Paulo; Martins, Ana Pimenta; Teixeira, Carla; Abreu, Helena; Silva, Joana Gabriela; Silva, Ana Machado; Freitas, Ana Cristina; Gomes, Ana MariaNutrition plays a crucial role in health promotion and disease prevention, and dietary-related factors are, in many cases, the leading risks for worldwide mortality and morbidity. Nowadays, consumer awareness of this fact has led to an increasing interest in food products that couple both these dimensions to an imperative third overall factor of interest—sustainability. Microalgae and seaweeds have in their composition a wide range of important multifunctional bioactive compounds which may possess cardiovascular protective, anti-inflammatory, anti-hypertensive, antioxidant, anti-coagulant, anti-proliferative, and/or antidiabetic activities. In addition, they can constitute excellent ingredients for the food industry to be used in the development of value-added food products. This review provides an overview on the current scientific and industrial developments regarding food products incorporating microalgae and seaweeds. Furthermore, technological, nutritional, sustainability, and health benefits resulting from their incorporation in different food matrixes are also explored
- Physical processing or supplementation of feeds with phytogenic compounds, alginate oligosaccharide or nucleotides as methods to improve the utilization of Gracilaria gracilis by juvenile European seabass (Dicentrarchus labrax)Publication . Valente, Luisa M.P.; Batista, Sónia; Ribeiro, Catarina; Pereira, Ricardo; Oliveira, Beatriz; Garrido, Inês; Baião, Luís F.; Tulli, Francesa; Messina, Maria; Pierre, Ronan; Abreu, Helena; Pintado, Manuela; Kiron, ViswanathThis study assessed both the effectiveness of a physical-mechanical rupture method and the ability of feed additives (phytogenic compounds, alginate oligosaccharide and nucleotides) to enhance the utilization of G. gracilis by European seabass. A commercial-based diet was used as control diet (CTRL) and compared with five isoproteic (53.5% Dry matter, DM) and isolipidic (14.9% DM) diets containing 8% of G. gracilis. This seaweed was either unprocessed (diet GRA) or subjected to physical processing (diet GRAP). The three additive-containing diets were formulated by supplementing the GRA diet with either 0.02% phytogenic compounds (PHY), 2.5% oligo-alginate (OAS) or 0.08% free nucleotides (NUC). Triplicate groups of nineteen fish (29.7 ± 0.02 g) were distributed by 50 L tanks (11.3 kg m−3) and fed the experimental diets to satiety during 106 days. By the end of the trial, growth performance and nutrient utilization (specific growth ratio, feed conversion ratio, apparent digestibility coefficients, nutrient balance, intestinal brush border membrane enzyme activities and plasma metabolic parameters), gut histomorphology, antioxidant and immunological status of fish were evaluated. The ability of fish to digest seaweed-rich diets was largely improved by the technological processing of G. gracilis, albeit nil effect on fish specific growth rate (1.0 in all groups). This major achievement was associated with increased ability of GRAP to digest protein (84 vs 68% in GRA) and energy (64 vs 38% in GRA). The use of feed additives in Gracilaria-rich diets was less efficacious in improving European sea bass nutrient and energy ADCs, but have still improved the overall digestibility of those diets. Fish fed alginate oligosaccharide was mainly associated with increased activity of anterior intestine enzymes, particularly intestinal alkaline phosphatase (IAP; 174.4 vs 104.7–120.6 μm min−1 g−1 in Gracilaria-rich diets). Moreover, the algae technological processing and both the nucleotides and the alginate oligosaccharide seem to have positively affected the intestinal villus width compared to the negative impact seen in fish fed GRA. The tested additives had limited impact on oxidative stress, although glutathione peroxidase (GPx; 2.1 μmol min−1 mg protein−1) and catalase (CAT; 35 μmol min−1 mg protein−1) activities were lowest in fish fed NUC and PHY, respectively. It can be concluded that the physical processing of Gracilaria sp. or the addition of either oligo-alginate or nucleotides can effectively increase the nutritional value of this seaweed for European seabass diets.
- Use of technological processing of seaweed and microalgae as strategy to improve their apparent digestibility coefficients in European seabass (Dicentrarchus labrax) juvenilesPublication . Batista, Sónia; Pintado, Manuela; Marques, Alexandra; Abreu, Helena; Silva, Joana L; Jessen, Flemming; Valente, Luísa M.P.Algae are natural sources of nutrients, but the presence of anti-nutritional factors often compromises nutrient apparent digestibility coefficients (ADCs) in several fish species. In this study, physical-mechanical and enzymatic technological processing was applie to two seaweeds (Gracilaria gracilis and Ulva rigida) and three microalgae (Nannochloropsis oceanica, Chlorella vulgaris, and Tetraselmis sp.) in order to evaluate its effectiveness in improving nutrient ADC values in diets for European seabass. A practical commercial-based diet was used as reference (REF) and experimental diets were prepared by replacing 30% of REF diet with each test alga used either intact or after processing. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and fast performance liquid chromatography (FPLC) analyses revealed that enzymatic processing was more effective than the physical one in changing the protein and peptides composition, increasing the amount of low-molecular-weight compounds in seaweeds and N. oceanica microalgae. Protein digestibility was significantly affected by algae species and in the case of the microalgae by the technological process. Gracilaria gracilis is better digested than U. rigida and physical processing enhanced protein and energy ADC values. Nannochloropsis oceanica and C. vulgaris are better digested than Tetraselmis sp.; the highest protein and energy ADCs were observed in diets containing enzymatically processed N. oceanica (NAN-ENZ) and physically processed C. vulgaris (CHLO-PHY), followed by the diet with physically processed Tetraselmis sp. (TETR-PHY). Results clearly showed that it is possible to increase nutrient accessibility and digestibility of algae by fish, by selecting the most adequate method to disrupt the cell wall. Moreover, the physical-mechanical and enzymatic technological processes used in this study are scalable to the industrial level.