a b s t r a c tSugarcane bagasse pretreated with dilute-acid was submitted to an organosolv ethanol process with NaOH under different operational conditions (pretreatment time, temperature, and ethanol concentration) aiming to maximize the glucose yield in the subsequent enzymatic hydrolysis stage. The different pretreatment conditions resulted in variations in the chemical composition of the solid residue as well as in the glucose recovered by enzymatic hydrolysis. All the studied variables presented significant (p < 0.05) influence on the process. The optimum organosolv pretreatment conditions consisted in using 30% (v/v) ethanol at 195 • C, during 60 min. Enzymatic hydrolysis of the residue then obtained produced 18.1 g/l glucose, correspondent to a yield of 29.1 g glucose/100 g sugarcane bagasse. The scale-up of this process, by performing the acid pretreatment in a 10-l semi-pilot reactor fed with direct steam, was successfully performed, being obtained a glucose yield similar to that found when the acid pretreatment was performed in autoclave.

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BACKGROUND: The organosolv pretreatment followed by enzymatic hydrolysis of the pretreated material and subsequent fermentation of the hydrolysate produced, was the strategy used for ethanol production from sugarcane bagasse. The effect of different operational variables affecting the pretreatment (the catalyst type and its concentration, and the pretreatment time) and enzymatic hydrolysis stage (substrate concentration, cellulase loading, addition of xylanase and Tween 20, and the cellulase/β-glucosidase ratio), were investigated.

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The high cost of cellulolytic enzymes used in the ethanol production process has led to a growing interest in situ production. The evaluation of the influence of several factors in the fungus Penicillium sp. cellulase production using pretreated sugarcane bagasse is very interesting. Penicillium sp. cellulase production by using filter paper as cellulosic substrate and the use of glucose, sucrose and lactose like co-substrates was assessed. In the experiments using filter paper as a cellulosic substrate, the highest FPase enzyme activity obtained was 280 FPU.L-1 using sucrose as co-substrate. Subsequently, the study of pretreated sugarcane bagasse was conducted using Plackett-Burman experimental design with analysis of 6 factors influencing the process. The highest FPase activity was 615.1 FPU.L-1. The factors influencing FPase and β- glucosidase activity were the use of molasses and the solid loading. The successful use of molasses as co-substrate opens perspectives for future researches.