Browsing by Author "Cavaco, Teresa"
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- Caracterização química e bioquímica dos frutos de ARBUTUS UNEDO L. e de RUBUS FRUTICOSUS AGG.: contribuição para a sua valorizaçãoPublication . Cavaco, Teresa; Carvalho, Isabel Saraiva deO presente trabalho teve como principal objectivo caracterizar quimicamente dois frutos silvestres, o fruto de Arbutus unedo L (medronho) e o fruto de Rubus fruticosus Agg. (amora), que crescem espontaneamente na Serra do Caldeirão. Os parâmetros físico-químicos e bioquímicos estudados foram o pH, o ºBrix, a humidade, a cinza total, os iões cálcio, magnésio, sódio e potássio, o azoto total, a proteína total, os açúcares (frutose, glucose e sacarose) e as antocianinas (delfinidina 3- glucosido, delfinidina 3,5-diglucosido, cianidina 3-glucosido, cianidina 3,5-diglucosido, pelargonidina 3-glucosido e pelargonidina 3,5- diglucosido). Foram ainda determinados os parâmetros de cor no espaço CIE (L*, a* e b*). Observaram-se diferenças significativas nas várias determinações físico-químicas realizadas dependendo do ano e do local de colheita das amostras. Os frutos de Arbutus unedo L apresentaram na sua constituição teores das antocianinas delfinidina 3-glucosido e cianidina 3-glucosido de 0,44 mg e 0,13 mg por 100 g de fruto fresco, respectivamente. Os frutos de Rubus fruticosus Agg. apresentaram na sua composição concentrações das antocianinas cianidina 3-glucosido, pelargonidina 3- glucosido e pelargonidina 3,5- diglucosido de 0,45 mg, 0,01 mg e 0,012 mg por 100 g de fruto, respectivamente. Estes frutos constituem, assim, uma fonte de antocianinas benéficas para a saúde, uma vez que estes compostos possuem reconhecidas actividades antioxidante e antimicrobiana. Foram também estudadas as alterações físico-químicas e microbiológicas da massa do fruto de Arbutus unedo L. em fermentação. As leveduras foram os microrganismos responsáveis pela fermentação, encontrando-se as bactérias lácticas e as bactérias acéticas ausentes no processo estudado. Os resultados obtidos contribuem para a valorização das espécies vegetais estudadas pois permitem que elas conquistem novos mercados, tendo em conta a sua composição em antocianinas e, consequentemente, contribuam para uma agricultura mais sustentável a nível económico, social e ambiental.
- Changes in physical and chemical parameters of the traditional portuguese product água-mel during the production processPublication . Figueira, A.C.; Cavaco, TeresaChanges in physical and chemical parameters (viscosity, total soluble solids and Hunter color parameters L*, a*, b*, chroma and hue angle) of água-mel were investigated throughout processing. Kinetic parameters for color change of heatprocessed água-mel were monitored. A zero-order kinetic model was applied to changes in L* and b*, while a* and C* were described using a first-order kinetic model. The heating process changed all three color parameters (L*, a*, b*), causing a shift toward the darker colors. Parameters L* decreased, while a*, b*, C* and hue angle (°h) increased during heating. Regarding changes in total soluble solids and in apparent viscosity, both fitted first-order kinetics. A direct relationship was found between the changes in these two parameters. The increase in both total soluble solids and viscosity affected a*, b* and C*. In addition, a flow diagram for the Portuguese água-mel production process has been established.
- Chemical and microbial changes during the natural fermentation of strawberry tree (Arbutus unedo L.) fruitsPublication . Cavaco, Teresa; Longuinho, Carla; Quintas, Célia; Carvalho, Isabel Saraiva deAguardente de medronho is the name given in Portugal to a spirit made from the fermented fruit of Arbutus unedo (strawberry tree), a plant grown in the Mediterranean region. In order to gain a better understanding of the fermentation process, as it is performed in the farms, a natural fermentation with wild microbiota was carried out during 36 days, and some physicochemical and microbiological parameters were studied. The microbial parameters analyzed were total viable, lactic and acetic acids bacteria, and yeast counts. The physicochemical parameters monitored were sugars, minerals, ethanol, organic acids and pH. Yeasts were the main responsible for the fermentation of the fruits, as the lactic and acetic acids bacteria are absent. As the fermentation progressed, the sugars increased during the first 2 days and gradually decreased along the fermentation period. Maintaining the good quality of the product could contribute to the preservation and valorization of traditional resources that are of great importance to prevent their disappearance.
- Cracked green table olive from the south of Portugal: the influence of diferent brining conditonsPublication . Rodrigues, Neusa; Cavaco, Teresa; Quintas, Célia; Nunes, CarlaIn the south of Portugal, cracked green olives represent a traditional way of processing table olives. After harvesting and sorting, the olives are washed, broken and immediately brined (Process A) or submitted to various washing steps with water prior to brining (Process B). The objective of this work was to study the effect of different processing treatments on the evolution of microbiological and physicochemical parameters during the fermentation of cracked green olives at a homemade scale and at different temperatures (25 ºC, room temperature and 18 ºC). Yeasts were found to be the dominant group in fermented cracked green table olives. Process A originated brines without countable Enterobacteria, with higher free acidity and higher phenolic content, when compared to brines resulting from Process B, suggesting that cracking and brining them straight away, represent a preferable way of processing olives which may guarantee the safety of the final product.
- Effect of photoperiod on flavonoid pathway activity in sweet potato (Ipomoea batatas (L.) Lam.) leavesPublication . Carvalho, Isabel Saraiva de; Cavaco, Teresa; Carvalho, Lara M.; Duque, PaulaCompared with those of major commercial leafy vegetables, leaves of sweet potato have higher contents of flavonoids and phenolic acids, which provide significant health benefits and may be used as natural colourants. We have analysed the expression of key flavonoid biosynthesis genes using RT-PCR and the accumulation of polyphenolic compounds using high-performance liquid chromatography coupled to a photodiode-array detector, during the development of leaves of sweet potato plants growing under either long day or short day photoperiods. A massive induction of flavonoid pathway gene expression, correlating with a dramatic increase in the content of an anthocyanin, catechins, flavonols, hydroxycinnamic acids and hydroxybenzoic acids, was observed during sweet potato leaf exposure to a long day photoperiod. These results provide further support for the protective role of flavonoids and phenolic acids against enhanced light exposure in plants.
- Evolution of physicochemical parameters during the thermal-based production of água-mel, a traditional Portuguese honey-related food productPublication . Cavaco, Teresa; Figueira, Ana Cristina; González-Domínguez, Raúl; Sayago, Ana; Fernández-Recamales, ÁngelesThe purpose of this work was to investigate the physicochemical changes occurring during the thermal-based production of água-mel, a traditional Portuguese honey-related food product. The refractive index, color parameters (hue angle, H°; chroma, C*), and the content of total reducing sugars, glucose, fructose, total brown pigments, and 5-hydroxymethylfurfural were monitored along the entire production process, and their evolution was kinetically modelled. Thermal processing caused a gradual decrease in sugars, which was accompanied by the formation of brown pigments and 5-hydroxymethylfurfural, increased concentration of soluble solids as evaluated through refractive index measurements, as well as the appearance of darker colors. In particular, a zero-order kinetic model could explain the changes in H° and reducing sugars, while the evolution of refractive index, brown pigments, 5-hydroxymethylfurfural, C*, fructose, and glucose were best fitted using a first-order kinetics model.
- Feiras de atividades em ciências para a educação pré-escolar concretizadas na Escola Superior de Educação e Comunicação da Universidade do AlgarvePublication . Coelho, Ana Cristina; Dionísio Gonçalves, C.; Cavaco, Teresa; Baião, Ana; Correia, Raquel; Horta, Maria Helena; Guerreiro, AntónioEm 2006, as alunas da licenciatura em Educação de Infância da ESEC – Universidade do Algarve, que frequentavam a unidade curricular (UC) anual de Atividades e Recursos em Ciências, organizaram, no âmbito da UC, a primeira feira de atividades em ciências dirigida a crianças dos jardins de infância.
- Phenolic composition and antioxidant capacity of six Artemisia speciesPublication . Carvalho, Isabel Saraiva de; Cavaco, Teresa; Brodelius, AnaThe aim of this work was to establish the antioxidant capacities and the polyphenolic profile of six different Artemisia species that could potentially be used in the human diet. A high-performance liquid chromatographic method coupled with photodiode-array detector was used to identify and quantify individual phenolic compounds of the Artemisia leaves. A total of 18 polyphenolic compounds were identified and quantified in Artemisia leaves, including hydroxybenzoic acids (4), hydroxycinnamic acids (5), flavonols (3), and catechins (2). It was observed that total phenolic content of A. annua and A. stelleriana leaves were significantly lower than the other four species. Ferulic and caffeic conjugates acids were the most dominant hydroxycinnamic acid and gallic acid and catechin were the most dominant hydroxycinnamic acid and catechins respectively. According to DPPH assays, the antioxidant capacity of A. arborescens spp., A. ludoviciana spp., A. oleandica spp. and A. princepts spp., were found to be higher (reflecting a 2-fold difference) than that of the other two species. Compared with those of major commercial leafy vegetables, leaves of Artemisia contain a higher content of flavonoids and phenolic acids, which provide significant health benefits and may be used as natural colorants.