DigitUMa

University of Madeira Institutional Repository

Bem-vindo ao Repositório Digital da UNIVERSIDADE DA MADEIRA.

O Repositório da Universidade da Madeira (UMa), conhecido pelo acrónimo DigitUMa, tem como objetivo a disponibilização, em regime de livre acesso e texto integral, de toda a produção científica realizada pelos docentes, investigadores da UMa, discentes dos 2º e 3º ciclos e pelos funcionários.

O Repositório Institucional, DigitUMa, assenta na política de Acesso Aberto à informação e conhecimento científicos.

Email antonio.freitas@staff.uma.pt

Recent Submissions

Influence of cold pre-fermentation maceration on the volatilomic pattern and aroma of white wines

Publication . Alti-Palacios, Laura; Martínez, Juana; Teixeira, José A. C.; Câmara, José S.; Perestrelo, Rosa; Câmara, José; Perestrelo, Rosa

Aroma compounds play a key role in wine quality due to their importance in wine aroma. The aim of the present study is to investigate the influence of cold pre-fermentative maceration (CPM) treatment on aromatic and sensory properties of white wines from four grape varieties (Tempranillo Blanco, Maturana Blanca, Viura and Garnacha Blanca) during two consecutive years (2019 and 2020). A total of 62 aroma compounds belonging to different chemical families were identified using headspace solid-phase microextraction combined with gas chromatography mass spectrometry (HS-SPME/GC-MS). CPM treatment enhanced the total relative concentration of alcohols, esters and acids compared to control wines. Regarding sensorial properties, esters made the greatest contribution to the studied white wines, mainly through the development of floral and fruity notes. On the other hand, CPM treatment did not significantly influence the total relative concentration of terpenoids, and different trends were observed according to grape variety and vintage. The obtained results showed differences in the wine’s aromatic complexity according to the grape variety, the vintage and the treatment applied and suggested that CPM treatment could represent a suitable approach to manipulate the aromatic profile and enhance the aromatic quality and complexity of wine.

2023-03-08Journal article

Open access

An improved analytical approach based on µ-QuEChERS combined with LC-ESI/MS for monitoring the occurrence and levels of Patulin in commercial apple juices

Publication . Câmara, José S.; Fernandes, Paulo; Barros, Nelson; Perestrelo, Rosa; Câmara, José; Perestrelo, Rosa

Patulin (PAT) is a mycotoxin produced in fruits, especially in apples, by diverse fungal species that can be transferred into industrial apple juice during processing. An accurate, effective, and selective method has been validated for the quantification of PAT in different commercial apple juices by combining a modified µ-QuEChERS procedure with high-pressure liquid chromatography (LC) equipped with a triple quadrupole mass spectrometer (QqQMS). This sample extraction procedure reduced interference from the sugar-rich matrix, and the separation was performed using the C18 Atlantis T3 column within 10 min. PAT was found by MS with electrospray negative ionization (ESI−) in the mode of multiple reaction monitoring (MRM). The correlation coefficient (R2 = 0.999) satisfied the prerequisite of linearity for PAT in the concentration range of 2–50 μg/kg. The limits of detection (LOD) and quantification (LOQ) of PAT were 0.32 and 1.15 μg/kg, respectively, which were compliant with the maximum levels settled in Commission Regulation (EC) No. 1881/2006. The recoveries were within the 92–103% range, at three fortified levels of 2, 20 and 50 μg/kg, with relative standard deviations lower than 7%. Based on analytical validation, it was confirmed that the µ-QuEChERS/HPLC-MS/MS method is an enhanced, reliable, and quick approach for determination of PAT in apple juice. The current approach proposes reduced sample preparation and analysis time. In addition, it is economical, environmentally friendly, and simpler to implement in comparison to traditional approaches.

2023-02-23Journal article

Open access

Relatório de estágio para obtenção do grau de mestre em Educação Pré-Escolar e Ensino do 1.º Ciclo do Ensino Básico

Publication . Nunes, Ana Luísa Martins; Mendes, Guida Reis Rodrigues

Reconhecendo a importância da reflexão na prática docente, o presente relatório apresenta uma descrição e reflexão sobre o processo de aquisição de conhecimentos e competências no desenvolvimento de práticas pedagógicas, para a obtenção do grau de mestre em Educação Pré Escolar e Ensino do 1.º Ciclo do Ensino Básico. As Práticas Pedagógicas foram realizadas em diferentes contextos, nomeadamente na Educação Pré-Escolar e no 1.º Ciclo do Ensino Básico, mais especificamente, em turmas de 1.º e 4.º ano de escolaridade. Neste sentido, o documento encontra-se estruturado em duas partes, sendo a primeira relativa aos pressupostos teóricos e metodológicos que sustentam as Práticas Pedagógicas, presentes na segunda parte. Tendo em conta a organização do sistema educativo português, os documentos orientadores da prática docente e o perfil do docente relativos à Edução Pré-Escolar e ao 1.º Ciclo do Ensino Básico, foram privilegiadas estratégias pedagógicas baseadas no construtivismo, dando à/ao criança/aluno um papel ativo no processo de ensino e aprendizagem, para que num trabalho de cooperação entre o docente e os aprendizes, fossem construídas aprendizagens significativas. Assim sendo, recorreu-se à metodologia de projeto, à metodologia de investigação-ação, à aprendizagem cooperativa, a situações de jogo e aos materiais didáticos para a promoção de aprendizagens. Em todas as Práticas Pedagógicas realizou-se um projeto com a comunidade, visando uma aprendizagem integrada de saberes, quer a nível curricular, quer a nível social. Considerando a importância de práticas educativas centradas nos aprendizes, o conhecimento das suas caraterísticas, a avaliação formativa e a reflexão foram grandes auxiliares para colmatar necessidades educativas e para a planificação de momentos de aprendizagem significativos e contextualizados. Por conseguinte, este relatório é uma partilha de experiências obtidas nas Práticas Pedagógicas com o objetivo de proporcionar momentos de aprendizagem contextualizados, significativos e enriquecedores às/aos crianças/alunos. Estas experiências constituem aprendizagens para a futura prática docente.

2025-07-09Master thesis

Open access

Evaluation of the transfer and occurrence of opium alkaloids in poppy seed teas using preconcentrations with µSPEed® followed by GC-MS analysis

Publication . Casado-Hidalgo, Gema; Perestrelo, Rosa; Morante-Zarcero, Sonia; Câmara, José S.; Sierra, Isabel; Câmara, José; Perestrelo, Rosa

Intoxication due to the consumption of poppy seed teas has been reported due to their contamination with opium alkaloids (OAs). In this work, an efficient methodology based on microsolid-phase extraction (µSPEed®) followed by gas chromatography–mass spectrometry (GC-MS) has been optimized to quantify five OAs in poppy seed teas. Nine cartridges (C4, C8, C18, silica, APS, PFAs, PS/DVB-RP, PS/DVB-SCX and PS/DVB-SAX), pH levels, cycles and elution solvents were evaluated. The method was validated and applied to study the transfer of OAs by evaluating water temperatures, infusion times and seed amounts. The highest transfer rates (71% for morphine, 96% for thebaine, and 100% for codeine, noscapine and papaverine) were achieved at 90°C, 5 min, with 4 g. These conditions were used to quantify the OAs in four teas prepared from different seeds. A high amount of morphine (1563 µg/L) was found in one tea, indicating that the seeds had a concentration twice the maximum limit, highlighting the need to warn the population of this dangerous practice.

2023-01-27Journal article

Open access

Bioactive compounds and antioxidant activity from spent coffee grounds as a powerful approach for Its valorization

Publication . Andrade, Carolina; Perestrelo, Rosa; Câmara, José S.

Coffee is one of the world’s most popular beverages, and its consumption generates copious amounts of waste. The most relevant by-product of the coffee industry is the spent coffee grounds, with 6 million tons being produced worldwide per year. Although generally treated as waste, spent coffee grounds are a rich source of several bioactive compounds with applications in diverse industrial fields. The present work aimed at the analysis of spent coffee grounds from different geographical origins (Guatemala, Colombia, Brazil, Timor, and Ethiopia) for the identification of bioactive compounds with industrial interest. For this purpose, the identification and quantification of the bioactive compounds responsible for the antioxidant activity attributed to the spent coffee grounds were attempted using miniaturized solid-phase extraction (µ-SPEed), combined with ultrahigh-performance liquid chromatography with photodiode array detection (UHPLC-PDA). After validation of the µ-SPEed/UHPLC-PDA method, this allowed us to conclude that caffeine and 5-caffeoylquinic acid (5-CQA) are the most abundant bioactive compounds in all samples studied. The total phenolic content (TPC) and antioxidant activity are highest in Brazilian samples. The results obtained show that spent coffee grounds are a rich source of bioactive compounds, supporting its bioprospection based on the circular economy concept closing the loop of the coffee value chain, toward the valorization of coffee by-products.

2022-11-03Journal article

Open access