Percorrer por autor "Vieira, Ana C."
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- Biorefinery of red macroalgae from Madeira archipelago for value-added productsPublication . Nunes, Nuno; Vieira, Ana C.; Odenthal, Kilian; Miguel Â. A. Pinheiro de Carvalho; Nunes, Nuno; Leal Vieira, Ana Carolina; Odenthal, Kilian; Almeida Pinheiro de Carvalho, Miguel AngeloAbstract Red macroalgae represent an underexplored yet promising resource due to their rich composition in proteins, pigments, and bioactive compounds with potential uses in nutraceutical, pharmaceutical, and agricultural industries. However, despite their abundance in coastal regions many species remain neglected and the development of efficient extraction and valorisation methods is still limited. This work assesses the optimization of protein and phycoerythrin extraction from three abundant red macroalgae species, Grateloupia lanceola , Asparagopsis taxiformis , and Nemalion elminthoides collected in Madeira island. Its major objective was to study a new biorefinery concept. The response surface methodology (RSM) results indicate that G. lanceola , harvested from offshore fish farms, exhibits the highest concentrations of both protein (2967 mg L −1 ) and phycoerythrin (212 mg L −1 ) when subjected to specific extraction parameters such as higher biomass weight (400 g) and increased number of cycles (18) using the Solid–Liquid Extraction system. In contrast, A. taxiformis and N. elminthoides demonstrated varied extraction patterns, with A. taxiformis producing substantial protein concentrations (328 mg L −1 ) but lower phycoerythrin yields (11 mg L −1 ). Sequential biorefinery methods were also employed to obtain bioactive compounds, and polysaccharides extracts. G. lanceola yields the highest concentration of soluble proteins (6.25 ± 0.59 g (100 g) −1 dw) and polysaccharides (11.13 ± 4.85 g (100 g) −1 dw), while N. elminthoides showed superior bioactive extract concentration (11.81 ± 0.31 g (100 g) −1 dw). The phenolic content in bioactive extracts has also been assessed using the Folin Ciocalteu method, finding a significant variation in total phenolic content among the species (1.38 ± 0.22 and 5.16 ± 0.06 mg GAE g −1 dw). The chromatographic analysis, formed by a Waters HPLC system and a photodiode array detector (Waters 2996) allowed to detect phenolic compounds within the bioactive extract, which include protocatechuic acid, hydroxybenzoic acid, epicatechin, p-coumaric acid and ferulic acid. Furthermore, the agronomic potential of the biorefinery residues was explored, revealing high nitrogen and phosphorus contents in liquid and solid residues, suggesting their potential to be used as biofertilizers. These findings contribute to the development of sustainable extraction processes for bioactive compounds from red macroalgae, enhancing the efficiency of biorefinery strategies and promoting the marine biomass valorization.
- Nutritional and phytochemical composition of Vaccinium padifolium Sm wild berries and radical scavenging activityPublication . Carvalho, Maria J.; Gouveia, Carla S.; Vieira, Ana C.; Pereira, Ana C.; Carvalho, Miguel Â.; Marques, José C.Blueberries have a well-deserved reputation as a potential functional food, supported by studies which have identified and quantified various nutrients and bioactive phytochemicals with known benefits for human diet and health. Wild blueberries have attracted particular attention due to the levels and concentrations of those phytonutrients. This study aims to evaluate for the first time the chemical composition of Madeira Island's endemic Vaccinium padifolium Sm wild berry. Results show that this fruit contains high values of total soluble phenolic content (around 4 g GAE kg-1 FW), as well as significant values of total monomeric anthocyanin content (around 3 g eq. cyanidin kg-1 FW) and DPPH scavenging activity (around 86.72%). Additionally, results reveal that this fruit has water content of about 88% as well as low sugar content (17.98 and 29.73 g kg-1 for glucose and fructose, respectively). Results also confirm that this wild blueberry is a good source of dietary fiber, fat and minerals. The high level of terpenoid compounds stands out in the aroma profile analysis.
- Optimal design of experiments applied to headspace solid phase microextraction for the quantification of vicinal diketones in beer through gas chromatography-mass spectrometric detectionPublication . Leça, João M.; Pereira, Ana C.; Vieira, Ana C.; Reis, Marco S.; Marques, José C.Vicinal diketones, namely diacetyl (DC) and pentanedione (PN), are compounds naturally found in beer that play a key role in the definition of its aroma. In lager beer, they are responsible for off-flavors (buttery flavor) and therefore their presence and quantification is of paramount importance to beer producers. Aiming at developing an accurate quantitative monitoring scheme to follow these off-flavor compounds during beer production and in the final product, the head space solid-phase microextraction (HS-SPME) analytical procedure was tuned through experiments planned in an optimal way and the final settings were fully validated. Optimal design of experiments (O-DOE) is a computational, statistically oriented approach for designing experiences that are most informative according to a well-defined criterion. This methodology was applied for HS-SPME optimization, leading to the following optimal extraction conditions for the quantification of VDK: use a CAR/PDMS fiber, 5 ml of samples in 20 ml vial, 5 min of pre-incubation time followed by 25 min of extraction at 30 C, with agitation. The validation of the final analytical methodology was performed using a matrix-matched calibration, in order to mini mize matrix effects. The following key features were obtained: linearity (R2 > 0.999, both for diacetyl and 2,3-pentanedione), high sensitivity (LOD of 0.92 mg L 1 and 2.80 mg L 1 , and LOQ of 3.30 mg L 1 and 10.01 mg L 1 , for diacetyl and 2,3-pentanedione, respectively), recoveries of approximately 100% and suitable precision (repeatability and reproducibility lower than 3% and 7.5%, respectively). The applicability of the methodology was fully confirmed through an independent analysis of several beer samples, with analyte concentrations ranging from 4 to 200 g L 1