Juliana Alexandra Barreto Peixoto

Ms. Juliana Alexandra Barreto Peixoto

ICETA (Instituto de Ciências, Tecnologias e Agroambiente da Universidade do Porto)
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orcid

Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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11 June 2020 in Separations
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COCatarina Osório
Catarina Osório
SMSusana Machado
Susana Machado
Juliana Alexandra Barreto PeixotoJuliana Alexandra Barreto Peixoto
Juliana Alexandra Barreto Peixoto
SBSílvia Bessada
Sílvia Bessada
FPFilipa Pimentel
Filipa Pimentel
Beatriz OliveiraBeatriz Oliveira
Beatriz Oliveira
Algae are a complex, polyphyletic group of organisms, affordable and naturally rich in nutrients, but also valuable sources of structurally diverse bioactive substances such as natural pigments. The aim of this work was to evaluate the polar and non-polar pigment contents of different commercial dried algae (brown: Himanthalia elongata, Undaria pinnatifida, Laminaria ochroleuca; red: Porphyra spp.; and a blue-green microalga: Spirulina spp.). The pigment extraction was carried out using different solvents (100% methanol, 100% methanol acid free, 100% ethanol, 90% acetone, N,N-dimethylformamide, dimethyl sulfoxide-water (4:1, v/v) and pH 6.8 phosphate buffer), selected according to their affinity for each class of pigments. Acetone proved to be an efficient solvent to extract chlorophylls from brown and red algae, but not from Spirulina spp. Porphyra spp. presented considerably higher levels of all pigments compared to brown algae, although Spirulina spp. presented significantly higher (p < 0.05) levels of chlorophylls, carotenoids and phycobiliproteins, compared to all macroalgae. The content of fucoxanthin extracted from the three brown algae was highly correlated to the carotenoid content. Within this group, Himanthalia elongata presented the highest fucoxanthin/total carotenoids ratio. Although the yield of extraction depended on the solvent used, the algae studied herein are an interesting source of pigments of great value for a wide range of applications.

8 December 2022 in Comprehensive Reviews in Food Science and Food Safety
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Juliana Alexandra Barreto PeixotoJuliana Alexandra Barreto Peixoto
Juliana Alexandra Barreto Peixoto
JSJoana F. Silva
Joana F. Silva
Beatriz OliveiraBeatriz Oliveira
Beatriz Oliveira
Rita Carneiro AlvesRita Carneiro Alves
Rita Carneiro Alves
The coffee industry is one of the most important commercial value chains worldwide. Nonetheless, it is also associated to several social, economic, and environmental concerns that impair its sustainability. The present review is focused on these main sustainability concerns from the field to the coffee cup, as well as on the strategies that are being developed and/or implemented to attain sustainability and circular economy principles in the different chain segments. In this context, distinct approaches have been applied, such as sustainable certifications (e.g., voluntary sustainability standards), corporate sustainability initiatives, direct trade, relationship coffee concepts, geographical indication, legislations, waste management, and byproducts valorization, among others. These strategies are addressed and discussed throughout this review, as well as their recognized advantages and limitations. Overall, there is still a long way to go to attain the much‐desired sustainability in the coffee chain, being essential to join the efforts of all actors and entities directly or indirectly involved, namely, producers, retailers, roasters, governments, educational institutions (such as universities and scientific research institutes), and organizations.

23 March 2021 in Antioxidants
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Juliana Alexandra Barreto PeixotoJuliana Alexandra Barreto Peixoto
Juliana Alexandra Barreto Peixoto
GÁGerardo Álvarez-Rivera
Gerardo Álvarez-Rivera
Rita Carneiro AlvesRita Carneiro Alves
Rita Carneiro Alves
ACAnabela S.G. Costa
Anabela S.G. Costa
SMSusana Machado
Susana Machado
Beatriz OliveiraBeatriz Oliveira
Beatriz Oliveira
The phenolics profile, free amino acids composition, and antioxidant potential of rosemary infusions were studied. Forty-four compounds belonging to nine different groups (hydroxybenzoic acids, hydroxycinnamic acids, flavan-3-ols, flavanones, flavones, phenolic diterpenes, hydroxybenzaldehydes, coumarins, and pyranochromanones) were identified by UHPLC-ESI-Q-TOF-MS. Of these, seven were firstly described in rosemary infusions: a rosmanol derivative, two dihydroxycoumarin hexosides, a hydroxybenzaldehyde, a dihydroxybenzoic acid hexoside, coumaric acid hexoside, and isocalolongic acid. The free amino acid profile of the beverages was also reported by the first time with seven amino acids found (asparagine, threonine, alanine, tyrosine, phenylalanine, isoleucine, and proline). Furthermore, DPPH• scavenging ability, Ferric Reducing Antioxidant Power and Oxygen Radical Absorbance Capacity, as well as total phenolics and flavonoids contents, were assessed. Overall, rosemary infusions showed to be a very good source of antioxidants. A 200 mL cup of this infusion contributes to the ingestion of ~30 mg of phenolic compounds and about 0.5–1.1 μg of free amino acids. This type of beverages may present a positive impact on the maintenance of the body antioxidant status and contribute to the prevention of oxidative stress related diseases.

7 June 2022 in Foods
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Juliana Alexandra Barreto PeixotoJuliana Alexandra Barreto Peixoto
Juliana Alexandra Barreto Peixoto
Nelson AndradeNelson Andrade
Nelson Andrade
SMSusana Machado
Susana Machado
ACAnabela S.G. Costa
Anabela S.G. Costa
Helder PugaHelder Puga
Helder Puga
Rita Carneiro AlvesRita Carneiro Alves
Rita Carneiro Alves
This study investigates the possibility of valorizing coffee silverskin through the recovery of its bioactive compounds using a sustainable extraction method that could be industrially applied. For that, aqueous extracts were prepared using ultrasonic-assisted extraction (laboratorial scale) and, for comparison, a scale-up of the process was developed using the Multi-frequency Multimode Modulated technology. A concentration procedure at the pilot scale was also tested. The three types of extracts obtained were characterized regarding caffeine and chlorogenic acids contents, and the effects on intestinal glucose and fructose uptake (including sugar transporters expression) in human intestinal epithelial (Caco-2) cells were ascertained. The phytochemical contents of the extracts prepared at the laboratory and pilot scale were comparable (caffeine: 27.7 vs. 29.6 mg/g freeze-dried extract; 3-, 4-, and 5-caffeoylquinic acids: 0.19 vs. 0.31, 0.15 vs. 0.42, and 1.04 vs. 1.98 mg/g, respectively; 4- and 5- feruloylquinic acids: 0.39 vs. 0.43 and 1.05 vs. 1.32 mg/g, respectively). Slight differences were noticed according to the extracts preparation steps, but in general, all the extracts promoted significant inhibitions of [1,2-3H(N)]-deoxy-D-glucose and 14C-D-fructose uptake, which resulted mainly from a decrease on the facilitative glucose transporter 2 (GLUT2) and sodium-glucose linked transporter 1 (SGLT1) genes expression but not on the expression of the facilitative glucose transporter 5 (GLUT5) gene. Moreover, a synergistic effect of caffeine and 5-caffeoylquinic acid on sugars uptake was found. The results clearly show that the Multi-frequency Multimode Modulated technology is a viable option to be applied at an industrial level to recover bioactive components from silverskin and obtain extracts with antidiabetic potential that could be used to develop functional food products or dietary supplements.

3 December 2022 in Foods
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Juliana Alexandra Barreto PeixotoJuliana Alexandra Barreto Peixoto
Juliana Alexandra Barreto Peixoto
Nelson AndradeNelson Andrade
Nelson Andrade
SMSusana Machado
Susana Machado
ACAnabela S.G. Costa
Anabela S.G. Costa
Beatriz OliveiraBeatriz Oliveira
Beatriz Oliveira
Rita Carneiro AlvesRita Carneiro Alves
Rita Carneiro Alves
Moderate coffee ingestion has been associated with a decrease in type 2 diabetes risk, mainly due to its richness in chlorogenic acids (CGA). To explore this, extracts of green beans, roasted beans, and silverskin were prepared by aqueous ultrasound-assisted extraction and characterized by a reversed-phase high-performance liquid chromatography-photodiode array detector (RP-HPLC-DAD). The effects on the uptake of glucose and fructose by human intestinal epithelial (Caco-2) cells and the influence on the expression of sugar transporter genes (by RT-qPCR) were investigated and compared. The uptake of 3H-deoxy-D-glucose and 14C-fructose by Caco-2 cells was significantly reduced by all the extracts, with green coffee (which also contained higher amounts of CGA) achieving the highest efficiency. Although silverskin presented the lowest amounts of CGA and caffeine, it promoted an inhibitory effect similar to the effects of green/roasted beans. In the case of glucose uptake, the effect was even higher than for roasted coffee. This activity is explained by the ability of the extracts to markedly decrease GLUT2, but not GLUT5 gene expression. In addition, a decrease in SGLT1 gene expression was also found for all extracts, although not at a statistically significant rate for silverskin. This study also revealed a synergistic inhibitory effect of caffeine and 5-CQA on the uptake of sugars. Thus, silverskin appears as an interesting alternative to coffee, since the valorization of this by-product also contributes to the sustainability of the coffee chain.

18 July 2024 in Food Bioscience
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Diana Isabel Lopes de Melo FerreiraDiana Isabel Lopes de Melo Ferreira
Diana Isabel Lopes de Melo Ferreira
Juliana Alexandra Barreto PeixotoJuliana Alexandra Barreto Peixoto
Juliana Alexandra Barreto Peixoto
NANelson Andrade
Nelson Andrade
SMSusana Machado
Susana Machado
CSCláudia Silva
Cláudia Silva
Rita Carneiro AlvesRita Carneiro Alves
Rita Carneiro Alves