Ethanol Fermentation of Microwave-assisted Acid Hydrolysate of Cassava Pulp with Saccharomyces cerevisiae in the Presence of Activated Carbon

摘要

The use of activated carbon has been proved could increase glucose yield from microwave-assisted hydrolysis of cassava pulp in water medium, but not in acid medium. The aim of this research was to study the effects of activated carbon addition on the fermentation of cassava pulp hydrolysate. In this work the fermentation of cassava pulp hydrolysates produced from microwave-assisted acid hydrolysis, either of those with or without activated carbon, was performed. The results of the fermentation were also compared with those resulted from hydrolysates treated with activated carbon for inhibitors adsorption before the fermentation. The hydrolysis was conducted in 0.88% sulfuric acid at 20% substrate concentration, 50% or 550 W microwave power level for 9 min. The amount of activated carbon added was 25% (w/w). The fermentation was performed in a gyratory shaker (150 rpm) at room temperature with Saccharomyces cerevisiae LIPI MC 0070 for 120 h. The samples were taken every 24 h for analysis of pH, total sugar, reducing sugar, glucose and ethanol. At the end of the fermentation ethanol yield and concentration obtained in samples treated with activated carbon (27-28% of dry matter; 34-35 g/L) were lower than those without activated carbon or those with activated carbon added after hydrolysis (31-32% of dry matter; 38-39 g/L). However, the fermentation was completed very much faster in the hydrolysates with activated carbon which has a high adsorption property than in those without activated carbon or with activated carbon of low adsorption property. Therefore, ethanol productivity (0.44-0.55 g/L/h) of the former was higher than the latter (0.28-0.34 g/L/h).