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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.2019.tde-20191218-164323
Document
Author
Full name
Valentina de Fatima de Martin
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 1987
Supervisor
Title in Portuguese
Efeito da remoção de células sobre o rendimento da fermentação alcoólica por leveduras
Keywords in Portuguese
FERMENTAÇÃO ALCOÓLICA
LEVEDURAS
REMOÇÃO DE CÉLULAS
RENDIMENTO
Abstract in Portuguese
A maior parte das indústrias brasileiras produtoras de etanol trabalham com o processo de Melle-Boinot, o qual consiste essencialmente em centrifugar a levedura apos completada a fermentação e reutilizar a mesma levedura no próximo ciclo fermentativo. O presente trabalho visou basicamente estudar em escala de laboratório, o efeito da remoção de quantidades crescentes de células de levedura do processo (sangria) entre os ciclos fermentativos, sobre o rendimento da fermentação alcoólica. Os experimentos foram conduzidos com a levedura prensada tipo Fleischmann (Saccharomyces cerevisiae) em mosto de xarope a 30°C e 33°C, em mosto de melaço a 33°C e com a linhagem M-300-A (S. cerevisiae) em mosto de xarope a 33°C. Após cada ciclo fermentativo foram retirados 5%, 10%, 15% e 20% (v/v) de células, durante sete ciclos. Foram determinados viabilidade e brotamento celulares, número de células/ml, matéria seca, bactérias/ml e açucares redutores residuais. A partir dos resultados das análises do vinho foi calculado o rendimento da fermentação alcoólica. Os resultados indicaram que, em escala de laboratório, a remoção de 5% a 20% (v/v) de células produziu os seguintes efeitos: - aumentou a viabilidade e o brotamento celular da levedura tipo Fleischmann e não teve influência sobre a linhagem M-300-A; - diminuiu o número de células e o teor de matéria seca de ambas as linhagens de levedura; - diminuiu o rendimento da fermentação para ambas as linhagens de levedura.
Title in English
Effect of the cells removal on the yield of alcoholic fermentation by yeasts
Abstract in English
Almost all the Brazilian ethanol plants production work on the Melle-Boinot process, which consist essentially in centrifuging out the yeast after the fermentation is completed and reusing the same yeast in the next fermentation cycle. The present work was undertaken to study on laboratory scale, the effect of the removal of increasing amounts of the yeast cells from the process (sangria) among the fermentative cycles on the alcoholic fermentation yield. The experiments were performed, with Fleischmann pressed yeast (Saccharomyces cerevisiae) in must of sugar cane syrup at 30°C and 33°C, must of molasses at 33°C, and with yeast strain M-300-A (S. cerevisiae) in must of sugar cane syrup at 33°C. After each fermentation cycle, 5%, 10%, 15% and 20% (v/v) of cells were removed,·by seven cycles. The cell viability, budding and the number of cells/ml, dry matter, bacterial cells/ml and residual reducing sugar were determined. From the results of the fermented must analysis, the fermentation yield was calculated. The results showed that, on a laboratory scale, the removal of cells from 5% up to 20% (v/v) had the following main effects: - increase in cell viability and in cell budding for the Fleischmann pressed yeast but had no effect on the M-300-A strain; - decrease in number of cells/ml and in dry matter for both strains of yeast; - decrease in fermentation yield for strains of yeast.
 
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Publishing Date
2019-12-19
 
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