Browsing by Author "Matos, Susana"
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- Avaliação dos compostos fenólicos e atividade antioxidante em mirtilos de diferentes proveniências geográficasPublication . Matos, Susana; Guiné, Raquel; Gonçalves, Fernando; Teixeira, DanielaO consumo de bagas tornou-se popular entre os consumidores preocupados com a saúde devido aos seus altos níveis de compostos fenólicos com propriedades antioxidantes [1]. Os mirtilos têm atraído atenção especial devido à sua alta capacidade antioxidante e elevada concentração de antocianinas e outros compostos fenólicos, tornando-a numa das frutas mais desejáveis e nutritivas [2]. Para além das antocianinas, os mirtilos também constituem uma boa fonte de ácido clorogénico, quercetina, kaempferol, miricetina, procianidinas, catequina, epicatequina, resveratrol e vitamina C, que contribuem para a sua atividade antioxidante [3]. Foram avaliados mirtilos da cultivar Bluecrop colhidos em diferentes regiões de Portugal (Estarreja, Vouzela, Vila Verde, Sever do Vouga e Oliveira do Hospital) com o objectivo de avaliar a influência da região de produção na composição fenólica e na capacidade antioxidante. De cada lote foram usadas 5 g de amostra trituradas, as quais foram subsequentemente submetidas a extrações sucessivas, primeiro 2 vezes com metanol e depois 2 vezes com uma solução aquosa de acetona (40% v/v), durante 1 h, com o auxílio de um banho de ultrassons. Os extratos obtidos foram utilizados para a determinação do teor em compostos fenólicos totais, em antocianinas e taninos. Foi ainda determinada a capacidade antioxidante utilizando os métodos ABTS e DPPH. No que respeita ao teor em compostos fenólicos totais a amostra proveniente de Vouzela revelou-se a mais rica (5,9 mg EAG/g) seguida da amostra de Estarreja (5,2 mg EAG/g), sendo que amostra menos rica de entre as estudadas foi a de oliveira do hospital (3,1 mg EAG/g). No que respeita ao conteúdo em antocianinas, amostra mais rica é a de Sever do Vouga (0,96 mg EMv/g) e a menos rica der todas a de oliveira do Hospital com 0,54 mg EMv/g. O teor em taninos variou de 1,82 a 3,53 mg/g, sendo a amostra com maior conteúdo em taninos a proveniente de Estarreja e aquela com menor conteúdo a de Oliveira do Hospital. A atividade antioxidante avaliada pelo método DPPH revelou que a amostra de Vouzela apresentou a maior capacidade antioxidante de entre as amostras estudadas (3,03 mg ET/g), e a de Oliveira do Hospital a menor (1,03 mg ET/g). Já no que respeita aos resultados obtidos com o método ABTS, verificaram-se diferenças sendo que a amostra com maior atividade antioxidante a de Estarreja (2,53 mg ET/g) e a que apresenta menor atividade antioxidante a de Vila Verde (1,67 mg ET/g). Em conclusão, verificou-se que de uma forma geral os mirtilos provenientes de Vouzela e Estarreja são os que se revelaram mais ricos em compostos fenólicos e que também apresentam maior atividade antioxidante, enquanto os de Oliveira do Hospital são os menos ricos em fenóis e também com menor atividade antioxidante.
- Evaluation of phenolic compounds and antioxidant activity of blueberries and modelization by artificial neural networksPublication . Guiné, Raquel; Matos, Susana; Gonçalves, Fernando J.; Costa, Daniela; Mendes, MateusThe study aimed at evaluating the influence of different production conditions, conservation and extraction procedures on the total phenolic compounds and antioxidant activity of blueberries by DPPH and ABTS methods. The production factors considered were origin, altitude of the farm location and age of the bushes. The conservation conditions considered were freezing as opposed to the fresh product. The extraction procedures included two different solvents and two orders of extraction. The data analysis was carried out by training artificial neural networks to model the data and extract information from the model. The results obtained revealed that the type of extract and the order of extraction influenced the concentrations of phenolic compounds as well as the antioxidant activity of the different samples studied. Also the origin of the farms from where the blueberries were harvested significantly influence those properties, showing that the blueberries from Oliveira do Hospital had less phenolic compounds and lower antioxidant activity. Also older bushes at higher altitudes seem to produce berries richer in these properties. Regarding conservation, no influence was observed for phenols but a slight influence could be detected for antioxidant activity.
- Evaluation of the physical-chemical properties of blueberries from diferente geographic originPublication . Matos, Susana; Guiné, Raquel; Gonçalves, Fernando; Costa, DanielaBlueberries are very popular for their potential health benefits around the world, from USA to Asia and to the Mediterranean. In the present work blueberries from cultivar Bluecrop harvested in different regions of Portugal (Estarreja-ES, Vouzela-VZ, Vila Verde-VV, Sever do Vouga-SV and Oliveira do Hospital-OH) were analysed to evaluate their physical-chemical properties: moisture content, total soluble solids (ºBrix) acidity, calibre, colour and texture. Moisture was evaluated by drying until constant weight, sugar content by refractometry and acidity by titration. Calibre was evaluated with a caliper rule, colour with a colorimeter in the CIELab colour space, and texture with a texturometer by measuring force in compression with a 2 mm probe P/2. The results showed that the sample VV had the highest moisture content as compared to all other varieties (83%), whereas the sample OH showed the highest acidity (0.79 mg citric acid/100g) and the sample ES the highest total soluble solids content (14,65 ºBrix). The average calibre ranged from 0.90 cm for sample SV to 1.17 cm for sample OH. Regarding the colour parameters it was observed that lightness (L*) was under 50, thus indicating that the samples are dark, whereas a* was around 0, so neither red nor green and b* was negative in all cases, so the colour is blue instead of yellow. The values of L* ranged from 31.07 to 36.79, respectively for samples VV and VZ; a* ranged from -0.02 to 0.62, respectively for samples VZ and VV; b* ranged from -7.76 to -5.02, respectively for samples ES and OH. The skin firmness varied from 11.0 N to 15.1 N, respectively for samples VZ and SV, while elasticity varied from 2.18 mm in the sample ES to 2.54 mm in the sample SV.
- Goat and sheep milk as raw material for yogurtPublication . Monteiro, António; Loureiro, Soraia; Matos, Susana; Correia, PaulaYogurts are prepared by bacterial fermentation of milk using bacterial cultures composed of a mixture of Streptococcus ssp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus. In the regions where small ruminants are important to the economy, the development of new products may and the diversification of the offer might represent good strategies to attract new consumers since it allows producers to go beyond the usual cheesemaking. Those were the reasons that led to the production of a yogurt that would include different proportions of sheep and goats milk, a final product with the right physicochemical quality properties and sensory attributes. The addition of sheep milk is meant to attract more and more potential consumers and to additionally improve the nutritional value of the product, mainly with respect to the amount of fatty acid and mineral contents. Consumers tend to prefer yogurts made of cow milk, but this work shows that people enjoy and accept yogurts produced with goat and sheep milk as well. Therefore, it seems evident that the milk produced by these small ruminants can be an alternative and has the potential to become a good food product.
- Modeling of the phenolic compounds and antioxidant activity of blueberries by artificial neural networks for data miningPublication . Guiné, Raquel; Matos, Susana; Costa, Daniela; Mendes, MateusThe present work’s goal was to evaluate the effect of different production and conservation conditions, as well as extraction procedures on the phenolic compounds and antioxidant activity of blueberries from cultivar Bluecrop. The production factors considered were origin, altitude of the farm location and age of the bushes, and the conservation was under freezing as opposed to the fresh product. The extraction procedures included two different solvents and different orders of the extraction. Data analysis was performed by training artificial neural networks to model the data and extract information from the model. The results showed that the type of extract and the order of extraction influence the concentrations of phenolic compounds as well as the antioxidant activity of the different samples studied. As to the origin of the farms from where the blueberries were collected, it was found to significantly influence these properties, so that the blueberries from Oliveira do Hospital showed less phenolic compounds and lower antioxidant activity. Older bushes at higher altitudes seem to produce richer berries. Regarding conservation, no influence was observed for phenols but a slight influence could be detected for antioxidant activity.
- Modeling the influence of production and storage conditions on the blueberry qualityPublication . Guiné, Raquel; Matos, Susana; Gonçalves, Christophe; Costa, Daniela Vasconcelos Teixeira da; Mendes, Mateus; Gonçalves, FernandoBlueberry is a widely consumed fruit with major economic value, appreciated due to its characteristic flavor as well as health benefits. The present work aimed to evaluate the effect of several production factors and storage conditions on some chemical and physical properties of blueberries. Some physical and chemical characteristics (moisture, acidity, sugars, color and texture) of blueberries from three cultivars, originating from five different locations and conventional or organic farming, were evaluated. The variation of the properties along time was also evaluated for storage at room temperature and refrigeration. Moreover, artificial neural network models were developed to estimate the physical-chemical characteristics of the blueberries, as influenced by the production and conservation factors considered. The results showed that all the characteristics considered varied according to cultivar, place of cultivation and production mode. The storage conditions also induced changes in the chemical components as well as in color and texture. The changes were dependent on type and duration of storage, cultivar and production mode. Weight analysis of the artificial neural network models highlighted the patterns and trends observed experimentally.
- Modelling Through Artificial Neural Networks of the Phenolic Compounds and Antioxidant Activity of BlueberriesPublication . Guiné, Raquel; Gonçalves, Christophe; Matos, Susana; Gonçalves, Fernando; Costa, Daniela Vasconcelos Teixeira da; Mendes, MateusThe present study aimed at investigating the influence of several production factors, conservation conditions, and extraction procedures on the phenolic compounds and antioxidant activity of blueberries from different cultivars. The experimental data was used to train artificial neural networks, using a feed-forward model, which gave information about the variables affecting the antioxidant activity and the concentration of phenolic compounds in blueberries. The ANN input variables were location, cultivar, the age of the bushes, the altitude of the farm, production mode, state, storage time, type of extract and order of extract, while the output variables were total phenolic compounds, tannins as well as ABTS and DPPH antioxidant activity. The ANN model was fairly good, with values of the correlation factor for the whole dataset varying from 0.948 to 0.979, while the values of mean squared error were ranging from 0.846 to 0.018, for DPPH antioxidant acidity and anthocyanins, respectively. The results obtained showed that the methanol extracts contained higher amounts of total phenols and anthocyanins as compared to acetone: water extracts, while presenting similar quantities of tannins in both extracts. The blueberries from organic farming were richer in phenolic compounds and possessed higher antioxidant activity than those from conventional agriculture. Even though the effect of storage was not established with high certainty, a trend was observed for an increase in the phenolic compounds and antioxidant activity along storage, either when under refrigeration or under freezing, for the storage periods evaluated.
- Statistical Analysis of the Factors that Influence the Properties of Blueberries from Cultivar BluecropPublication . Guiné, Raquel; Matos, Susana; Costa, Daniela; Gonçalves, FernandoBecause blueberries are worldwide recognized as a good source of beneficial components, their consumption has increased in the past decades, and so have the scientific works about their properties. Hence this work was undertaken to evaluate the effect of some production and conservation factors on the properties of blueberries from cultivar Bluecrop. The physical and chemical analyses were done according to established methodologies and then all data was treated using software SPSS for assessment of the possible differences among the factors investigated and/or the correlations between the variables at study. The results showed that location of production influenced some of the berries properties (caliber, sugars, antioxidant activity, color and texture) and that the age of the bushes was correlated with moisture, sugars and acidity, as well as lightness. On the other hand, altitude of the farm only was correlated to sugar content. With regards to conservation, it influenced only anthocyanins content and DPPH antioxidant activity. Finally, the type of extract and the order of extraction had a pronounced influence on all the phnolic properties evaluated
- Statistical Analysis of the Factors that Influence the Properties of Blueberries from Cultivar BluecropPublication . Guiné, Raquel; Matos, Susana; Costa, Daniela; Gonçalves, FernandoBecause blueberries are worldwide recognized as a good source of beneficial components, their consumption has increased in the past decades, and so have the scientific works about their properties. Hence, this work was undertaken to evaluate the effect of some production and conservation factors on the properties of blueberries from cultivar Bluecrop. The physical and chemical analyses were done according to established methodologies and then all data was treated using software SPSS for assessment of the possible differences among the factors investigated and/or the correlations between the variables at study. The results showed that location of production influenced some of the berries properties (caliber, sugars, antioxidant activity, color and texture) and that the age of the bushes was correlated with moisture, sugars and acidity, as well as lightness. On the other hand, altitude of the farm only was correlated to sugar content. With regards to conservation, it influenced only anthocyanins content and DPPH antioxidant activity. Finally, the type of extract and the order of extraction had a pronounced influence on all the phenolic properties evaluated.