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- Mead production: comparison of different production scales (preliminary results)Publication . Gomes, Teresa; Barradas, Carla; Dias, Teresa; Andrade, João Verdial; Morais, Jorge Sá; Ramalhosa, Elsa; Estevinho, Leticia M.Mead production represents a possible economic alternative to honey producers that intend to obtain honey products with surplus value. From that the present work aims to study the influence of using different production scales on the quality of the final mead obtained and on the process performance. Increasing the production scale almost ten times (1.5 to 20 L), some differences were observed. Maximum specific growth rates equal to 0.045 and 0.038 h-1 were obtained for fermentations carried out at 1.5 and 20 L, respectively. The time course of glucose and glycerol were similar for both production scales. Nevertheless, slight differences at the end of the fermentations were observed for fructose and acetic acid. In relation to ethanol, a higher final concentration was found in the pilot-scale, resulting in a higher ethanol yield. In conclusion, these preliminary results are a good promise to local honey producers who intent to obtain large-productions of mead.
- Mead production: comparison of different production scales (preliminary results)Publication . Gomes, Teresa; Barradas, Carla; Dias, Teresa; Andrade, João Verdial; Morais, Jorge Sá; Ramalhosa, Elsa; Estevinho, Leticia M.Mead production represents a possible economic alternative to honey producers that intend to obtain honey products with surplus value. From that the present work aims to study the influence of using different production scales on the quality of the final mead obtained and on the process performance. Increasing the production scale almost ten times (1.5 to 20 L), some differences were observed. Maximum specific growth rates equal to 0.045 and 0.038 h-1 were obtained for fermentations carried out at 1.5 and 20 L, respectively. The time course of glucose and glycerol were similar for both production scales. Nevertheless, slight differences at the end of the fermentations were observed for fructose and acetic acid. In relation to ethanol, a higher final concentration was found in the pilot-scale, resulting in a higher ethanol yield. In conclusion, these preliminary results are a good promise to local honey producers who intent to obtain large-productions of mead.
- Pesquisa de resíduos de fungicidas no mosto e no vinhoPublication . Pinto, Miguel; Pereira, Sandra; Fernandes, Conceição; Andrade, João Verdial; Estevinho, Leticia M.
- Mead production improvements after using a factorial desingPublication . Gomes, Teresa; Dias, Teresa; Andrade, João Verdial; Cadavez, Vasco; Morais, Jorge Sá; Ramalhosa, Elsa; Estevinho, Leticia M.Anexo
- Análise sensorial de vários tipos de hidromelPublication . Gomes, Teresa; Dias, Teresa; Andrade, João Verdial; Cadavez, Vasco; Morais, Jorge Sá; Ramalhosa, Elsa; Estevinho, Leticia M.A região de Trás-os-Montes e uma das grandes produtoras de mel no pais. No entanto, existe dificuldade em escoar a produção surgindo o hidromel como uma alternativa possível para ultrapassar este problema. Com base em resultados obtidos pela nossa equipa, este trabalho teve como objective avaliar as características sensoriais do hidromel produzido a escala piloto. Resultados anteriores indicam que a levedura Saccharomyces cerevisiae Fermol® Reims Champagne (Pascal Biotech®) á a mais indicada para a fermentação do hidromel. As condições ideais para a produção de hidromel obtidas com base no desenho experimental foram: temperatura entre os 24°C e os 29°C e concentração de sais entre 85 e 100 g/hL.
- Optimization of mead production using response surface methodologyPublication . Gomes, Teresa; Barradas, Carla; Dias, Teresa; Andrade, João Verdial; Morais, Jorge Sá; Ramalhosa, Elsa; Estevinho, Leticia M.The main aim of the present work was to optimize mead production using Response Surface Methodology. The effects of temperature (x1: 20–30 ºC) and nutrients concentration (x2: 60–120 g/hL) on mead quality, concerning the final concentrations of glucose (Y1), fructose (Y2), ethanol (Y3), glycerol (Y4) and acetic acid (Y5), were studied. Twelve operational conditions were tested. No delays and moods were observed during fermentations. The second order polynomial models determined produced satisfactory fittings of the experimental data with regard to glucose (R2= 0.646, p = 0.001), ethanol (R2= 0.741,p = 0.049), glycerol (R2= 0.899, p = 0.002), fructose (R2= 0.902, p = 0.033) and acetic acid (R2= 0.913,p = 0.001). The optimum extraction conditions determined in order to maximize the combined responses were 24 ºC and a nutrients concentration of 0.88 g/L. The mead produced under these conditions had the following characteristics: ethanol concentration of 10.2%, acetic acid 0.54 g/L, glycerol 7.8 g/L, glucose 1.8 g/L and fructose 2.5 g/L. These values were in agreement with the predicted and were within the safe limit established for acetic acid and the recommended range for glycerol. Furthermore, the residual sug- ars concentration was also low, decreasing the possibility of occurring undesirable refermentations.
- Estudo comparativo do comportamento enológico de levedurasPublication . Cruz, Fernando; Bessa, António; Andrade, João Verdial; Estevinho, Leticia M.Anexo
- Detecção de fenóis voláteis e leveduras do género Dekkera em vinhos de Trás-os-montesPublication . Rebelo, Fernanda; Estevinho, Leticia M.; Morais, Jorge Sá; Rocha, Amélia; Andrade, João VerdialOs fenóis voláteis são um grupo de compostos que podem estar presentes em vinhos exercendo urna forte influencia no seu aroma. Destacam-se neste grupo o 4-etil-fenol e o 4-etil-guaiacol, em vinhos tintos, e o 4-venil-fenol e 4-vinil-guaiacol em vinhos brancos. Estes compostos quando presentes em baixíssimas concentrações não prejudicam significativamente os aromas dos vinhos. No entanto, a medida que a concentração aumenta, sobretudo do 4-etil-fenol, começam a ser perceptiveis aromas que rapidamente levam a depreciagao dos vinhos, provocando consequenternente perdas económicas significativas aos produtores.
- Mead production: selection and characterization assays of Saccharomyces cerevisiaePublication . Pereira, Ana Paula; Dias, Teresa; Andrade, João Verdial; Ramalhosa, Elsa; Mendes-Ferreira, Ana; Mendes-Faia, Arlete; Estevinho, Leticia M.Mead is a traditional alcoholic drink which results from the fermentation of diluted honey. Yeasts used in mead production are, usually, wine Saccharomyces cerevisiae strains. Most of these yeasts are not adapted to the conditions of mead production namely, high sugar levels, low pH values and reduced nitrogen concentrations. The inability of yeast strains to respond and adapt to unfavorable stressful growth conditions, leads to several problems, such as lack of uniformity of the final product, delays and “pouts” fermentations, as well as the production of off-flavors by the yeasts. Therefore, it is necessary to find yeast strains more suitable for mead production.
- Mead production: selection and characterization assays of Saccharomyces cerevisiae strainsPublication . Pereira, Ana Paula; Dias, Teresa; Andrade, João Verdial; Ramalhosa, Elsa; Estevinho, Leticia M.Mead is a traditional drink, which results from the alcoholic fermentation of diluted honey carried out by yeasts. However, when it is produced in a homemade way, mead producers find several problems, namely, the lack of uniformity in the final product, delayed and arrested fermentations, and the production of “off-flavours” by the yeasts. These problems are usually associated with the inability of yeast strains to respond and adapt to unfavourable and stressful growth conditions. The main objectives of this work were to evaluate the capacity of Saccharomyces cerevisiae strains, isolated from honey of the Trás-os-Montes (Northeast Portugal), to produce mead. Five strains from honey, as well as one laboratory strain and one commercial wine strain, were evaluated in terms of their fermentation performance under ethanol, sulphur dioxide and osmotic stress. All the strains showed similar behaviour in these conditions. Two yeasts strains isolated from honey and the commercial wine strain were further tested for mead production, using two different honeys (a dark and a light honey), enriched with two supplements (one commercial and one developed by the research team), as fermentation media. The results obtained in this work show that S. cerevisiae strains isolated from honey, are appropriate for mead production. However it is of extreme importance to take into account the characteristics of the honey, and supplements used in the fermentation medium formulation, in order to achieve the best results in mead production.