Tuesday, April 20, 2010
11-29

Ethanol production from milk whey by use of beta-galactosidase and Saccharomyces cerevisiae

Ailton C. Andrade, Marcelo Pireti, Vicelma Luiz Cardoso, U. Coutinho Filho, and Euclides H. Araśjo. Faculty of Chemical Engineering, Uberlāndia Federal University, Uberlāndia, Brazil

Whey represents about 85-95% of milk volume and is produced in huge amount in dairy industry. There are several ways of utilizing, treating, and disposing of whey. But despite of this situation the growth of the cheesemaking industry produce increasingly larger quantities of non-utilized whey which have resulted in greater pollution hazards and an excellent opportunity to increase the production of ethanol from the cultivation of yeast. The objective of this work is to evalulate the ethanol production by Saccharomyces cerevisiae grown in whey. Twelve fermentations were done using 2000-mL glass fermentor with a working volume of 1800 mL. Two concentrations of beta-galactosidase from Aspergillus oryzae were tested: 0.2 and 0.4 g/L. When concentrated whey containg 65 g/L of lactose was used the best result gave maximum ethanol production efficiency with enzyme concetration, ethanol concentration, productivity, yield and substrate convertion of 0.4g/L, 30.1g/L, 3.01 g/(L.h), 0.48 g/g and 96.7% respectively. When whey containing 45 g/L of lactose was used the best results found were enzyme concentration of 0.4g/L, ethanol concentration of 21.1g/L , productivity of 2.63 g/(L.h), yield of 0.50 g/g and substrate convertion of 96.4%. The experimental results have been compared against calculations obtained by simulation. The experimental results has been found to be in a satisfying agreement with the model that described inhibition in the lactose hydrolysis and that the consumption rates of glucose were higher than galactose

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