Sunday, May 4, 2008
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Effects of the extraction with ethanol or cyclohexane/ethanol on the structural composition of sugarcane bagasse

Larissa Canilha1, Walter Carvalho2, Laura Danne F.O. Barbosa2, Ernesto A. Martinez1, João Batista Almeida e Silva2, and Marco Giulietti1. (1) Chemical Division, Institute of Technological Research, São Paulo, Brazil, (2) Department of Biotechnology, Engineering College of Lorena-University of São Paulo, Lorena, Brazil

The effects of submitting the sugarcane bagasse to a previous extraction with ethanol or cyclohexane/ethanol (2:1) in its structural composition were determined in this study. Such extraction not only affects the percentages of the main components determined after a two-step acid hydrolysis, but could also lead to a hemicellulosic hydrolysate with lower amounts of extractives, compounds that can inhibit the microbial activity. After milling, the bagasse was maintained in contact with each one of the solvents in a Soxhlet extractor until the solvent became colorless. After extensive washing with deionized water, the extracted bagasse was dried in an oven at 105 ºC and had its composition determined after two-step acid hydrolysis under standard conditions. According to the results, the structural compositions of the non-extracted bagasse, of the bagasse extracted with ethanol and of the bagasse extracted with cyclohexane/ethanol, respectively, were as follows: cellulose (46.9 ± 0.2, 46.1 ± 0.1 and 45.4 ± 0.3), hemicellulose (27.5 ± 0.1, 27.1 ± 0.2 and 26.2 ± 0.1), lignin (26.3 ± 0.7, 23.2 ± 0.4 and 21.5 ± 0.2), ashes (1.6 ± 0.0, 1.6 ± 0.0 and 1.5 ± 0.0) and extractives (0.0, 4.1 ± 0.1 and 6.1 ± 0.0). We observed that the relative percentages of cellulose, hemicellulose and ashes determined in the present study did not differ significantly from those determined previously in our Institution. On the other hand, the amount of extractives determined in this study was higher than those described previously (3.0 %, in average).
ACKNOWLEDGEMENTS: Fapesp and CNPq (Brazil)

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