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Advisor(s)
Abstract(s)
O mel é um produto natural, ao qual são reconhecidas propriedades físicas e
químicas que contribuem para a sua actividade biológica. No entanto, o mel
actualmente, é comercializado a preços reduzidos, tornando-se imperioso encontrar
alternativas que viabilizem as explorações apícolas nacionais. Uma destas alternativas
passa pela produção de hidromel.
Apesar das excelentes propriedades do mel, a produção de hidromel enfrenta
alguns problemas, nomeadamente, atrasos e amuos da fermentação, falta de
uniformidade do produto e produção de compostos, pelas leveduras, com aroma
desagradável. Estes problemas podem estar associados ao facto das leveduras utilizadas
na fermentação serem leveduras enológicas que, provavelmente, não estão adaptadas às
condições de stress do mel.
Este trabalho teve como objectivos a caracterização do mel da região de
Trás-os-Montes (Nordeste de Portugal), a selecção de leveduras isoladas de mel para a
produção de hidromel e a optimização das condições de produção de hidromel.
A primeira parte do trabalho consistiu na caracterização do mel utilizado na
produção de hidromel. O mel analisado mostrou ser um produto de qualidade, que
cumpria os parâmetros estabelecidos na legislação portuguesa.
Na segunda parte avaliou-se a capacidade de estirpes de Saccharomyces
cerevisiae isoladas de mel português para produzir hidromel. Para tal, cinco estirpes
isoladas de mel, uma estirpe de referência e uma estirpe comercial, utilizada em
enologia, foram avaliadas e comparadas em termos da sua resistência ao sulfuroso, ao
etanol, e stress osmótico. Todas as estirpes exibiram um comportamento semelhante às
condições de stress estudadas.
Destas estirpes foram seleccionadas a comercial e, aleatoriamente, duas estirpes
isoladas de mel para a produção de hidromel. As três estirpes foram submetidas a
fermentações com dois méis diferentes (um claro e um escuro) enriquecidos com dois
suplementos (1: comercial; 2: desenvolvido pela equipa de investigação). Para avaliar o
desempenho das fermentações determinou-se o crescimento da levedura e a produção de
etanol, glicerol e ácido acético. As estirpes de Saccharomyces cerevisiae isoladas de
mel mostraram ser apropriadas para a produção de hidromel. No entanto, é necessário
ter em consideração as características do mel e dos suplementos utilizados na
formulação do meio de fermentação.
Honey is a natural product with recognized physical and chemical properties, which contribute to its biological activity. However, honey is currently being sold at low prices, making it imperative to find alternatives to make apiculture a viable national enterprise. One of these alternatives could be mead production. Despite the excellent properties of honey, mead production faces several problems, namely, delays and “pouts” fermentations, lack of uniformity of the product and production of off-flavours by the yeasts. These problems can be usually associated with the fact, the yeast used in fermentation are yeast wine, which probably will not be adapted to the stress of honey. The main objectives of this work were the characterization of Trás-os-Montes (Northeast Portugal) honey, the selection of yeasts isolated from honey for mead production and the optimization of conditions for mead production. The first part of the work consisted in the characterization of honey used in the mead production. The analysed honey has shown to be a quality product that met the parameters established in Portuguese legislation. In the second part, the ability of Saccharomyces cerevisiae strains isolated from Portuguese honey to produce mead was evaluated. So, five strains isolated from honey, a reference strain and a commercial strain used in oenology, were evaluated and compared in terms of their resistance to ethanol, sulphur dioxide and osmotic stress. All strains exhibited similar behaviour to the conditions of stress studied. Of these strains, for mead production it were selected two strains isolated from honey (randomly) and the commercial one. The three strains were subjected to fermentations with two different honeys (a light and a dark honeys) enriched with two supplements (1: commercial; 2: developed by research the team). To evaluate the fermentation performance it was determined the yeast growth and the production of ethanol, glycerol and acetic acid. The Saccharomyces cerevisiae strains isolated from honey had shown to be appropriate for mead production. However, it is necessary to have into account the characteristics of the honey and supplements used in the fermentation medium formulation.
Honey is a natural product with recognized physical and chemical properties, which contribute to its biological activity. However, honey is currently being sold at low prices, making it imperative to find alternatives to make apiculture a viable national enterprise. One of these alternatives could be mead production. Despite the excellent properties of honey, mead production faces several problems, namely, delays and “pouts” fermentations, lack of uniformity of the product and production of off-flavours by the yeasts. These problems can be usually associated with the fact, the yeast used in fermentation are yeast wine, which probably will not be adapted to the stress of honey. The main objectives of this work were the characterization of Trás-os-Montes (Northeast Portugal) honey, the selection of yeasts isolated from honey for mead production and the optimization of conditions for mead production. The first part of the work consisted in the characterization of honey used in the mead production. The analysed honey has shown to be a quality product that met the parameters established in Portuguese legislation. In the second part, the ability of Saccharomyces cerevisiae strains isolated from Portuguese honey to produce mead was evaluated. So, five strains isolated from honey, a reference strain and a commercial strain used in oenology, were evaluated and compared in terms of their resistance to ethanol, sulphur dioxide and osmotic stress. All strains exhibited similar behaviour to the conditions of stress studied. Of these strains, for mead production it were selected two strains isolated from honey (randomly) and the commercial one. The three strains were subjected to fermentations with two different honeys (a light and a dark honeys) enriched with two supplements (1: commercial; 2: developed by research the team). To evaluate the fermentation performance it was determined the yeast growth and the production of ethanol, glycerol and acetic acid. The Saccharomyces cerevisiae strains isolated from honey had shown to be appropriate for mead production. However, it is necessary to have into account the characteristics of the honey and supplements used in the fermentation medium formulation.
Description
Keywords
Caracterização do mel Hidromel Saccharomyces cerevisiae Selecção de estirpes Fermentação Condições de stress Honey characterization Mead Saccharomyces cerevisiae Strain selection Fermentation Stress factors
Citation
Pereira, Ana Paula Rodrigues - Caracterização de mel com vista à produção de hidromel. Bragança: Instituto Politécnico, Escola Superior Agrária, 2008. Dissertação de Mestrado em Qualidade e Segurança Alimentar
Publisher
Instituto Politécnico de Bragança, Escola Superior Agrária