Produção de etanol pela fermentação alcoólica do permeado de soro de leite com Saccharomyces cerevisiae

Abstract

Whey is a by-product of cheese manufacturing, comprising a mixture of proteins, lactose, minerals, fat and water. It is estimated that the production of 1 kg cheese requires 10 liters of milk and provides 9 liters of whey, which can be regarded as a polluting agent to high BOD (Biological Oxygen Demand), or as a noble product, because the levels of soluble proteins and lactose. The whey permeate is formed when the whey pass through the process of membrane separation and centrifugation, where proteins and fats are removed, respectively. This study aimed to develop an 32 experimental design, varying the temperature and pH values on three levels, and evaluate the best condition for the fermentation of whey permeate, after the hydrolysis with the enzyme lactase (β-galactosidase), by Saccharomyces cerevisiae and performing analysis for the characterization and control of the permeate growth of biomass, pH and ethanol production during fermentation time. The present study was 12 fermentation trials for the conversion of glucose to ethanol with total fermentation time of 32 hours, use pH values, 4.0, 4.5 and 5.0, and temperatures of 25, 30 and 35 ° C. To the results it was developed the experimental design and It was possible to find the condition with increased ethanol production, this being used to a pH of 4.0 and a temperature of 35 ° C producing an amount of 41.80 g / L ethanol, with a yield of 75,80 %.