Browsing by Author "Barros, Ana"
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- Efeito da secagem na composição fenólica da pêra Rocha (Pyrus communis L.) de diferentes origens.Publication . Santos, Sandra; Guiné, Raquel; Barros, AnaA pera Rocha (Pyrus communis L.) é a principal cultivar produzida em Portugal, sendo habitualmente consumida em fresco. No entanto, a secagem da pera pode constituir uma oportunidade de desenvolvimento e possibilitar a oferta de produtos alternativos aos consumidores. Neste trabalho, estudou-se o efeito de duas temperaturas de secagem (40 e 60ºC) sobre os teores de fenóis totais e de actividade antioxidante. Para isso foram usadas peras provenientes de 5 localidades diferentes. No caso dos fenóis totais, os resultados mostraram que as principais diferenças ocorreram com a secagem a 60ºC. Relativamente à actividade antioxidante, ambas as secagens originaram diminuições acentuadas dos valores, relativamente às peras analisadas em fresco.
- Effect of drying temperatures on the phenolic composition and antioxidant activity of pears of Rocha variety (Pyrus communis L.)Publication . Santos, Sandra; Guiné, Raquel; Barros, AnaThe interest about phenolic compounds and antioxidant activity has been increasing in recent years, mainly due to their beneficial effects on human health, focusing on many different food products. In this way, and since pears are an important source of dietary intake of phenolic compounds with antioxidant activity, this work was done to evaluate the phenolic content and antioxidant activity of pears of cv. Rocha from five different locations and submitted to drying at different temperatures (40 and 60 C). Although the amounts of phenolic compounds are not very much influenced by drying, the antioxidant capacity does suffer a very marked decrease with drying at both temperatures, when compared to that of the fresh pears. The HPLC analysis of the phenolic extracts allowed identifying some phenolic compounds present in the pears, such as arbutin, gallic acid, chlorogenic acid, syringic acid, protocatechuic acid, catechin and epicatechin. From the results obtained in this study it was concluded that the greatest variations occurred in the peel of the pears, as compared to the corresponding pulps. Furthermore, it was possible to observe that while total phenols and ortho- diphenols do not seem to be very affected by drying, the antioxidant capacity suffers a great decrease with drying, being this effect more pronounced when the drying tem- perature is increased.
- Influence of Drying on the Properties of Pears of the Rocha Variety (Pyrus communis L.).Publication . Santos, Sandra; Guiné, Raquel; Barros, AnaRocha pear (Pyrus communis L.) is the main cultivar produced in Portugal, usually consumed in fresh. However, the drying of the pear can be an oppor- tunity for development and enables the provision of alternative products to consumers. This work evaluates the effect of drying on some chemical and physical properties of pears of the Rocha variety. Furthermore, the origin of the pears was also a variable studied. For the completion of this work, pears from five different locations were analysed in fresh and after convective air drying at two different temperatures, 40 and 60°C. The properties analysed were dimensions of pears in terms of height and diameter, total solids content, acidity, maturation index, processing yields, colour and textural attributes. The results showed that the peel had lower acidity and higher maturation index, when compared to the pulp and that drying greatly reduced acidity, either in the pulp or in the peel. However, this variation was not influenced by the drying temperature. With respect to colour, total colour differences between 25 and 50 were observed (for the dried pears in relation to the fresh) and in this case increasing the drying temperature caused evident variations in the peel but not in the pulp. As to the textural attributes, hardness and chewiness were the ones that showed the higher changes with drying, increasing considerably with drying temperature.
- Quercus spp. extract as a promising preventive or therapeutic strategy for cancer: A systematic reviewPublication . Oliveira, Paula; Medeiros-Fonseca, Beatriz; Vasconcelos-Nóbrega, Carmen; Alvarado, Antonieta; Pires, Maria; Vala, Helena; Barros, Ana; Faustino-Rocha, AnaAcorns have traditionally been used in the human diet and for the treatment of specific diseases. Therefore, the present study performed a systematic review of studies which investigated the effects of Quercus spp. extracts in cancer prevention and treatment. A systematic literature search was performed for original records which addressed the anticancer effects of Quercus spp. extract in in vitro and in vivo cancer models. Body composition, food consumption, tumor development and/or toxicity were evaluated in in vivo studies, while cytotoxicity was evaluated in in vitro studies. Few studies and low sample sizes presented a challenge in the drawing of solid conclusions. Overall, the results suggested a positive impact of Quercus spp. extract, by reducing cancer development. Therefore, more studies with different cancer cell lines and animal models to address the efficacy of the acorn extracts in several types of cancer are required. Furthermore, the effects of acorn flour, incorporated in the diet, in an animal model of mammary cancer should be evaluated.
- Solid vinaigrette – a newly developed food productPublication . Guiné, Raquel; Barros, Ana; Queirós, Ana; Pina, Andreia; Vale, Andreia; Ramoa, Helena; Folha, Joana; Carneiro, RaquelIn the last decades consumer demands in the field of food production has changed considerably. Consumers more and more believe that foods contribute directly to their health. Today foods are not intended to only satisfy hunger and to provide necessary nutrients for humans but also to prevent nutrition-related diseases and improve physical and mental well-being of the consumers. Therefore, new food products development must be inevitably directed to this new dimension of the concept of food. The phenomenon which has received significant publicity and media coverage during the last few years widely known as molecular gastronomy, and which is sometimes mistakenly seen as a cooking style, is a scientifically oriented approach towards understanding the basic mechanisms occurring during cooking. The objectives of the present work were to create an innovative product in the sector of the olive oil products, so highly valued in Mediterranean gastronomic cultures and Portugal in particular, by producing a texturized vinaigrette that, in addition to the benefits of the olive oil, offers a different dining experience to those who consume it. The main goal was to create an original product that fulfils the consumers’ needs and expectations. Vinaigrette is a mixture of oils olive oil, for example) with vinegar, forming an emulsion. Sometimes it is flavored with herbs, spices, and other ingredients, being used most commonly as a salad dressing, but it can also be used as a cold sauce or marinade. After preparing the product, making chemical analysis, texture profile analysis, sensory analysis and market research, it was found that although the product was very creative, and valued it could still be improved. Still, the results indicate that this product as it is could be well accepted by the consumers.
- Sugar composition of Rocha pear (Pyrus communis L.) – Influence of drying treatmentsPublication . Santos, Sandra; Guiné, Raquel; Barros, AnaRocha Pear (Pyrus communis L.) is the main cultivar produced in Portugal, and is classified as Protected Designation of Origin (PDO). Pear production represents a significant economic activity in Portugal (c.a. 190.000 tonnes per year), and the cultivar Rocha represents 95% of the National Product [1]. The pear contains sugars, vitamins, organic acids, polyphenols and minerals in considerable concentrations [2]. Pears are, usually, eaten fresh when ripe. However, the increase in the supply of processed products, particularly subjected to drying [3], may provide an opportunity for development and enable the provision of alternative products to consumers. The drying of fruits is a very ancient practice for food preservation still in use nowadays, once the process significantly reduces water activity [4]. In this work, pears of the variety Rocha harvested at different orchards (five different origins) were studied, fresh and dehydrated at two temperatures, 40 and 60 ºC, to determine and compare their sugar composition. This determination was made separately to the pulp and peel from each location. The results showed that pulps contained a higher amount of sugars (6-15%) than peels, both fresh and dried. Additionally, it was possible to verify that the drying treatment caused a reduction (35-50%) in the total amount of sugars. Sugar analysis showed that the relative composition of fresh pulps and peels was similar, both composed mainly by mannose, followed by sorbitol and glucose. The drying process reduced glucose levels and increased the relative amount of mannose in pulps, while sorbitol and manose increased in peels.
- Variação de propriedades de textura de pêra Rocha de diferentes proveniências.Publication . Santos, Sandra; Guiné, Raquel; Barros, AnaA pêra Rocha (Pyrus communis L.) é uma cultivar produzida em Portugal, com grande expressão nos mercados Português e internacional. É um produto tradicional classificado como Denominação de Origem Protegida (DOP), sendo portanto a sua produção e comercialização regulamentada. Devido ao facto de ter um bom potencial de armazenamento, é possível a sua distribuição para o mercado durante quase todo o ano, sendo este um aspecto importante que a diferencia competitivamente em relação a outras variedades (1). De entre os atributos de qualidade que caracterizam qualquer alimento, e a pêra em particular, a textura assume um papel fundamental, sendo um atributo sensorial de grande relevância para a aceitação do alimento pelo consumidor, em conjugação com a aparência e o sabor (2). É essencialmente uma experiência humana, que resulta da nossa interacção com o alimento. A textura caracteriza-se por um conjunto de propriedades físicas que são consequência da estrutura interna do material, que por sua vez é determinada pelas interacções moleculares dos seus constituintes. Os alimentos no geral, e as peras em particular, apresentam diferentes propriedades de textura, que derivam das diferenças inerentes à variedade, ao estado de maturação e às condições de produção (solo, clima, entre outras) (3). Neste trabalho, são objecto de estudo as peras da variedade Rocha no estado fresco, colhidas em diferentes pomares (quatro da região do Oeste e um da região da Beira Baixa), de forma a determinar e comparar entre si os respectivos atributos de textura. As propriedades de textura foram avaliadas pelo método de análise do perfil de textura (TPA), utilizando como instrumento de medida um texturómetro, TE.XT.Plus da Stable Micro Systems. Os parâmetros de textura avaliados foram a dureza, a adesividade, a coesividade, a elasticidade e a mastigabilidade. Nos lotes de peras das diferentes proveniências foram obtidos os TPAs em amostras obtidas para diferentes orientações, e incluindo ou não a casca. No sentido de caracterizar cada lote de peras no que respeita ao seu estado de maturação, foram feitas análises para determinação do teor de sólidos solúveis e teor de acidez, sendo o índice de maturação calculado como a razão entre estas duas propriedades. Dos resultados obtidos foi possível observar algumas variações nas propriedades de textura em função da proveniência dos lotes, nomeadamente entre os da região do Oeste e o da região da Beira Alta.