The sugarcane bagasse is, as any lignocellulosic material, mostly constituted by cellulose, hemicellulose and lignin. These three components amount to more than 90% of the dry weight of the fiber. The ash content is, in general, low. In turn, the non-fiber compounds, commonly referred as extractives, may represent a significant portion of the dry weight in the raw material. In the present study, samples of raw bagasse were extracted with water, ethanol and water followed by ethanol. Then, the extracted bagasses had their chemical compositions determined by a series of analyses based on the methods proposed by Browning (1967), with modifications. As can be seen in Table 1, the water extraction removed 5.8% of extraneous materials from the bagasse fibers. The ethanol extraction led to a similar content of extractives (5.6%). On the other hand, the sequential extraction with both solvents reduced the dry weight of the raw material in 9.4%, thus showing that these two solvents dissolved structurally different compounds. This assumption was further confirmed by the relative absorption spectra of the extracts (Figure 1).

Table 1: Chemical composition of the extracted samples of sugarcane bagasse

	Extractant
	Water	Ethanol	Water + Ethanol
Cellulose (%)	42.50	45.25	46.82
Hemicellulose (%)	24.88	27.29	26.84
Lignin (%)	20.90	18.93	19.76
Ash (%)	1.64	1.64	1.64
Extractives (%)	5.83	5.64	9.38
Sum (%)	95.75	98.75	104.44

Figure 1: Relative absorption spectra of the aqueous and alcoholic extracts

Acknowledgements: Fapesp (Brazil)