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- Comparative study of different Portuguese samples of propolis: pollinic, sensorial, physicochemical, microbiological characterization and antibacterial activityPublication . Dias, L.G.; Pereira, Ana Paula; Estevinho, Leticia M.The aim of this work was to study four propolis samples from Trás-os-Montes region of Portugal. The propolis samples’ color was different, which pollen analysis showed to be due to different botanical sources: Populus sp., Pinus sp., Quercus sp. and Castanea sativa. The data from physicochemical analysis (moisture, soluble and insoluble solids content, pH, conductivity, ash content, wax, total phenolics and flavonoids content) was treated using multivariate statistical tools as cluster heat map, principal components analysis and linear discriminant analysis with the purpose of classifying the sample accordingly to the botanical/geographical origin. The discriminant analysis was applied with stepwise to select the variables that most contribute to sample identification accordingly to pollinic profile. The cross-validation technique was applied, using the leave-one-out procedure, which showed good prediction capabilities of the samples. Microbiologically, the commercial quality was satisfactory, since the samples didn’t contain deterioration or pathogenic microorganisms. All the samples studied presented antimicrobial activity against Methicillin-resistant Staphylococcus aureus, in a dose dependent way. The antimicrobial activity was strictly related to the physicochemical composition. This work will allow connecting a particular chemical propolis type to a specific type of biological activity, what is essential for the use in therapeutic applications.
- Mead production: Fermentative performance of yeasts entrapped in different concentrations of alginatePublication . Pereira, Ana Paula; Mendes-Ferreira, A.; Estevinho, Leticia M.; Mendes-Faia, ArleteMead is an alcoholic drink known since ancient times, produced by yeast fermenting diluted honey. However, the production of mead has suffered in recent years, partially owing to the lack of scientific progress in this field. In this study, two strains of Saccharomyces cerevisiae, QA23 and ICVD47, were immobilized in 2 or 4% (w/v) alginate beads to assess the most effective alginate concentration for yeast immobilization to produce mead. Neither of the alginate concentrations was able to prevent cell leakage from the beads. The fermentation length was 120h for both yeast strains. In all cases, at the end of the fermentation, the number of cells entrapped in the beads was higher than the number of free cells, and the total 4% alginate bead wet weight was significantly higher than the 2% alginate bead wet weight. In addition, the evaluation of mead quality showed that the yeast strain had significantly more influence on the physicochemical characteristics than the alginate concentration. Although the yeasts immobilized in the two alginate concentrations were able to perform the fermentation, further research is needed in order to understand the evolution of the yeast population inside the beads throughout the fermentative process.
- Improvement of mead fermentation by honey-must supplementationPublication . Pereira, Ana Paula; Mendes-Ferreira, Ana; Estevinho, Leticia M.; Mendes-Faia, ArleteThrough honey's fermentation, diverse beverages can be obtained, among which is mead, an alcoholic drink with 8 to 18% of ethanol (v/v). Since honey is a matrix with a low nutrient concentration and other unfavourable growth conditions, several problems are usually encountered, namely delayed or arrested fermentations, unsatisfactory quality parameters and lack of uniformity of the final product, as well as unpleasant sensory properties. In this context, the aim of this work was to optimize mead production through honey-must supplementation with (a) salts, (b) vitamins or (c) salts+vitamins. The effects of the honey-must formulation on the fermentation kinetics, growth profile and physicochemical characteristics of final meads were evaluated. The results showed minor differences in the fermentation profile and time between fermentations with the different formulations. The growth profile was influenced more by the yeast strain than by the supplements added to the honey-must. In general, the honey-must composition did not influence meads' final characteristics, except regarding the SO < inf > 2 < /inf > concentration of the meads produced using the strain QA23. In summary, the addition of salts and/or vitamins to honey-must had no positive effects on the fermentation, growth profile or characteristics of the final products.
- Portuguese bee pollen: palynological study, nutritional and microbiological evaluationPublication . Estevinho, Leticia M.; Rodrigues, Sandra; Pereira, Ana Paula; Feás, XesúsBee pollen is one of the richest and purest natural foods, used in the folk medicine, clinical practices, and food and pharmaceutical industries. This work aims to characterise, for the first time in Portugal, the palynological origin, nutritional value and microbiological safety of this beehive product. It identified ten botanical families, and the more frequent were Boraginaceae and Ericaceae. We have evaluated the water content, aw, pH, reducing sugars, ash, carbohydrate, proteins, lipids, fatty acids and energy. The microorganisms studied were the aerobic mesophiles, moulds and yeasts, faecal coliforms, Escherichia coli, Staphylococcus aureus, Salmonella and sulphite-reducing clostridia. The studied pollens are nutritionally well balanced, and contain high levels of moisture, proteins, fat, energy, ash, carbohydrates, reducing sugars, essential n-3 fatty acids and good ratios of polyunsaturated fatty acids (PUFA)/saturated fatty acids. In fact, the PUFA represent 66% of the total fatty acids. The samples had good microbiological quality, as none of the samples had toxigenic species.
- An assessment of the processing and physicochemical factors contributing to the microbial contamination of salpicão, a naturally-fermented Portuguese sausagePublication . Cadavez, Vasco; Gonzales-Barron, Ursula; Pires, P.; Fernandes, E.; Pereira, Ana Paula; Gomes, Aline; Araújo, José Pedro; Lopes-da-Silva, M.F.; Rodrigues, Paula; Fernandes, Conceição; Saavedra, Maria José; Butler, Francis; Dias, TeresaComplete microbiological, physicochemical and environmental longitudinal data were obtained from factory surveys in order to elucidate risk factors leading to the survival of Enterobacteriaceae, Staphylococcus aureus and Listeria monocytogenes in salpicão sausage. A total of six batches were surveyed from two factories; one added nitrite and polyphosphates in their formulation (Factory II). The addition of polyphosphates slowed down fermentation, which favoured the increase in Enterobacteriaceae (∼0.5 log CFU/g), S. aureus (∼0.5 log CFU/g) and L. monocytogenes (∼70 CFU/g) until maceration. Maceration should be regarded as a critical stage in the control of S. aureus in salpicão, as longer maceration (p = 0.033), higher temperatures of maceration (p = 0.018) and pH of macerated meat (p = 0.079) led to higher S. aureus counts in the final product. The main hurdle controlling S. aureus in salpicão is the pH. For L. monocytogenes and Enterobacteriaceae, at least three hurdles hinder their viability: low Aw (p = 0.010; 0.012), smoking (p < 0.0001; 0.020) and nitrite (p = 0.158; 0.105). Cross-contamination, especially during mixing, should be avoided as it is an important factor explaining the increase in Enterobacteriaceae (p = 0.041), S. aureus (p = 0.015) and L. monocytogenes (p = 0.082) on a batch basis. There is a need to optimise the acidification process and reinforce good hygiene practices
- Manual de boas práticas de segurança e saúde no trabalho apícola uma abordagem para uma cultura de segurança no setorPublication . Pires, Sância; Martins, Vitor Manuel Ramalheira; Igrejas, Getúlio; Coelho, João Paulo; Machado, Ana; Pereira, Ana Paula; Nunes, SofiaA qualidade das condições de trabalho é um dos fatores fundamentais para o sucesso de um sistema produtivo e, o mesmo, também se aplica ao setor apícola. Nesse âmbito, a melhoria da produtividade e da competitividade depende, necessariamente, de uma intervenção no sentido da perceção e melhoria das condições de trabalho. Neste contexto, a elaboração de um Manual de Boas Práticas de Segurança e Saúde no trabalho apícola pretende dar continuidade ao incremento e transferência de conhecimentos técnicos aos apicultores e a todos os agentes envolvidos nesta atividade, contribuindo para uma melhor estruturação do setor. Tendo em consideração a reduzida quantidade de literatura que se encontra disponível, incluindo manuais e outros documentos referentes a Boas Práticas de Segurança e Saúde no trabalho apícola, considera-se que a elaboração de um manual, não vinculativo e de caráter orientador, poderá trazer um contributo relevante e pertinente para a atividade.
- Characterization of Lavandula spp. Honey Using Multivariate TechniquesPublication . Estevinho, Leticia M.; Chambó, Emerson Dechechi; Pereira, Ana Paula; Carvalho, Carlos Alfredo Lopes de; Toledo, Vagner de Alencar Arnaut deTraditionally, melissopalynological and physicochemical analyses have been the most used to determine the botanical origin of honey. However, when performed individually, these analyses may provide less unambiguous results, making it difficult to discriminate between mono and multifloral honeys. In this context, with the aim of better characterizing this beehive product, a selection of 112 Lavandula spp. monofloral honey samples from several regions were evaluated by association of multivariate statistical techniques with physicochemical, melissopalynological and phenolic compounds analysis. All honey samples fulfilled the quality standards recommended by international legislation, except regarding sucrose content and diastase activity. The content of sucrose and the percentage of Lavandula spp. pollen have a strong positive association. In fact, it was found that higher amounts of sucrose in honey are related with highest percentage of pollen of Lavandula spp.. The samples were very similar for most of the physicochemical parameters, except for proline, flavonoids and phenols (bioactive factors). Concerning the pollen spectrum, the variation of Lavandula spp. pollen percentage in honey had little contribution to the formation of samples groups. The formation of two groups regarding the physicochemical parameters suggests that the presence of other pollen types in small percentages influences the factor termed as "bioactive", which has been linked to diverse beneficial health effects.
- Volatile composition and sensory properties of meadPublication . Pereira, Ana Paula; Mendes-Ferreira, Ana; Dias, L.G.; Oliveira, José M.; Estevinho, Leticia M.; Mendes-Faia, ArleteMead is a traditional beverage that results from the alcoholic fermentation of diluted honey performed by yeasts. Although the process of mead production has been optimized in recent years, studies focused on its sensory properties are still scarce. Therefore, the aim of this work was to analyse the sensory attributes of mead produced with free or immobilized cells of the Saccharomyces cerevisiae strains QA23 and ICV D47, and to establish potential correlations with its volatile composition. In the volatile composition of mead, the e ect of yeast condition was more important than the strain. In respect to sensory analysis, the most pleasant aroma descriptors were correlated with mead obtained with free yeast cells, independently of the strain. Both sensory analysis and volatile composition indicates that the most pleasant mead was produced by free yeast cells. Although this study has provided a significant contribution, further research on the sensory quality of mead is still needed.
- Efeito da adição de pólen na produção de hidromel.Publication . Machado, Adriana; Pereira, Ana Paula; Estevinho, Leticia M.Em Portugal, a apicultura é uma atividade dirigida essencialmente para a produção de mel de alta qualidade. No entanto, ocorrem perdas de mel significativas durante os processos de extracção, embalamento e lavagem dos recipientes. Assim, para valorizar a região e aumentar o rendimento dos apicultores é importante aproveitar uma fracção do mel desperdiçado, como por exemplo, para a produção de hidromel. O hidromel é uma bebida alcoólica tradicional, que contém entre 8 a 18% (v/v) de etanol, que resulta da fermentação do mel diluído realizada por leveduras. No entanto, quando esta bebida é produzida com mel claro observam-se paragens e amuos da fermentação, provavelmente devido à limitação em nutrientes deste tipo de mel [1]. A utilização de pólen como ativador da fermentação apresenta-se como uma aposta favorável, devido à sua composição em proteínas, vitaminas, minerais e lípidos [2]. Este trabalho teve como objectivo avaliar o efeito da adição de diferentes concentrações de pólen (10, 30 e 50 g/L) na produção de hidromel, nomeadamente no desempenho fermentativo e nas características do produto final. Para a preparação do mosto foram utilizadas ceras de mel claro que foram lavadas de modo a atingir 23 ºBrix. O mel diluído foi suplementado com nutrientes comerciais e seguidamente, dividido para adicionar as diferentes concentrações de pólen. Paralelamente, foi preparado um mosto, sem adição de pólen, como controlo. Todos os mostos foram inoculados com a levedura enológica seca ativa Saccharomyces cerevisiae Lalvin QA23. As fermentações foram monitorizadas diariamente através da leitura da densidade óptica, determinação das unidades formadoras de colónias e quantificação dos açúcares redutores. No final das fermentações, a qualidade dos hidroméis foi avaliada através da determinação dos parâmetros enológicos pH, acidez volátil, acidez total, azoto assimilável, SO2 total e teor alcoólico. Na fermentação controlo observou-se uma paragem no consumo dos açúcares, ficando o hidromel com cerca de 100 g/L de açúcar residual. Por outro lado, a adição de pólen ao mosto, independentemente da sua concentração, estimulou a cinética de fermentação com o consumo completo dos açúcares. O hidromel produzido com concentrações de pólen de 30 e 50 g/L apresentou um teor alcoólico mais elevado. No entanto nestes hidroméis, também se verificou uma concentração mais elevada de azoto residual, sugerindo que a concentração de pólen adicionada poderá ter sido excessiva. Resumindo, neste estudo verificou-se que o pólen, particularmente adicionado em concentrações baixas, pode ser um ativador apropriado para suprimir a limitação de nutrientes, existente na produção de hidromel a partir de mel claro. Apesar dos resultados serem bastante promissores, é importante avaliar a influência da adição de pólen no perfil aromático e nas propriedades sensoriais do hidromel.
- Computational intelligence applied to discriminate bee pollen quality and botanical originPublication . Gonçalves, Paulo J.S.; Estevinho, Leticia M.; Pereira, Ana Paula; Sousa, João M.C.; Anjos, OféliaThe aim of this work was to develop computational intelligence models based on neural networks (NN), fuzzy models (FM), and support vector machines (SVM) to predict physicochemical composition of bee pollen mixture given their botanical origin. To obtain the predominant plant genus of pollen (was the output variable), based on physicochemical composition (were the input variables of the predictive model), prediction models were learned from data. For the inverse case study, input/output variables were swapped. The probabilistic NN prediction model obtained 98.4% of correct classification of the predominant plant genus of pollen. To obtain the secondary and tertiary plant genus of pollen, the results present a lower accuracy. To predict the physicochemical characteristic of a mixture of bee pollen, given their botanical origin, fuzzy models proven the best results with small prediction errors, and variability lower than 10%.