Publicação
Development of an integrated process for continuous winemaking
| Resumo: | Microorganisms play an important role in the food industry, particularly in the processing of foods and beverages. In wine production, two consecutive fermentation processes occurs, involving yeasts (alcoholic fermentation) and lactic acid bacteria (malolactic fermentation), its control is being crucial to obtain high quality products. Considering that the raw material used in wine production is seasonal these two fermentations are conducted in batch mode. The advances made in cell immobilization techniques in the last decade, led to further exploration of these techniques for continuous fermentation processes. This work aims at the implementation of a continuous wine production process by the use of sequential continuous fermentations with immobilized cells, in the different stages of the fermentative process of winemaking, i.e. in alcoholic fermentation and in malolactic fermentation. For this purpose, separate immobilization of commercial strains of Saccharomyces cerevisiae and Oenococcus oeni were carried out by adsorption on different natural waste materials such as: grape skins, grape stems, grape seeds and corn cobs. Following preliminary batch trials the best immobilized cell systems were studied in the corresponding packed bed reactors operated in continuous mode. The influence of the operating parameters of the system over the cell physiology and quality of the final product - physicochemical and sensory characteristics (colour, aroma and taste) - was evaluated. The operational stability of the immobilized systems was also characterized. Fermentations with immobilized cells were much faster than fermentations with free cells and the quality of the product was maintained, making the process more advantageous and economical. Also, the uses of natural supports that are agro-industrial residues make the process more environmentally friendly. The quality of the wines produced using immobilized cells was confirmed by sensory evaluation as it was difficult to distinguish between wines produced by the different methods. Volatile aroma compounds evaluation confirmed the good quality of wines produced with immobilized cells. Initially, wines produced with immobilized cells presented a darker colour compared with wines produced by the traditional free cells method. However, with time and with the reuse of the immobilized cell system the colour stabilized and wines became similar to the wines produced with free cells. The used immobilized cell systems were found to have strong operational and mechanical stabilities. Moreover it was found that immobilized cells can be stored for at least 1 month at 4 °C and used again in fermentation processes of winemaking, as confirmed by its successful application in continuous alcoholic and malolactic fermentation processes. Overall, the integrated continuous process of winemaking demonstrated to have good operational stability making it a valuable alternative for the production of good quality wines. |
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| Autores principais: | Genisheva, Zlatina Asenova |
| Ano: | 2013 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Microorganisms play an important role in the food industry, particularly in the processing of foods and beverages. In wine production, two consecutive fermentation processes occurs, involving yeasts (alcoholic fermentation) and lactic acid bacteria (malolactic fermentation), its control is being crucial to obtain high quality products. Considering that the raw material used in wine production is seasonal these two fermentations are conducted in batch mode. The advances made in cell immobilization techniques in the last decade, led to further exploration of these techniques for continuous fermentation processes. This work aims at the implementation of a continuous wine production process by the use of sequential continuous fermentations with immobilized cells, in the different stages of the fermentative process of winemaking, i.e. in alcoholic fermentation and in malolactic fermentation. For this purpose, separate immobilization of commercial strains of Saccharomyces cerevisiae and Oenococcus oeni were carried out by adsorption on different natural waste materials such as: grape skins, grape stems, grape seeds and corn cobs. Following preliminary batch trials the best immobilized cell systems were studied in the corresponding packed bed reactors operated in continuous mode. The influence of the operating parameters of the system over the cell physiology and quality of the final product - physicochemical and sensory characteristics (colour, aroma and taste) - was evaluated. The operational stability of the immobilized systems was also characterized. Fermentations with immobilized cells were much faster than fermentations with free cells and the quality of the product was maintained, making the process more advantageous and economical. Also, the uses of natural supports that are agro-industrial residues make the process more environmentally friendly. The quality of the wines produced using immobilized cells was confirmed by sensory evaluation as it was difficult to distinguish between wines produced by the different methods. Volatile aroma compounds evaluation confirmed the good quality of wines produced with immobilized cells. Initially, wines produced with immobilized cells presented a darker colour compared with wines produced by the traditional free cells method. However, with time and with the reuse of the immobilized cell system the colour stabilized and wines became similar to the wines produced with free cells. The used immobilized cell systems were found to have strong operational and mechanical stabilities. Moreover it was found that immobilized cells can be stored for at least 1 month at 4 °C and used again in fermentation processes of winemaking, as confirmed by its successful application in continuous alcoholic and malolactic fermentation processes. Overall, the integrated continuous process of winemaking demonstrated to have good operational stability making it a valuable alternative for the production of good quality wines. |
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