Composition of Residue from Sugarcane and Related Species.

In Louisiana, a facility near Jennings will produce cellulosic ethanol from sugarcane (Saccharum spp. hybrids) bagasse and “energy canes”. This study was done to obtain basic information on the composition of the cell wall residue left after expressing the juice in different Saccharum genotypes. Four commercial cultivars, five S. officinarum genotypes, and 22 wild S. spontaneum genotypes were grown in 38-L cans during the spring and summer of 2006. In August 2006, plants were harvested by cutting at soil level, chipped, and juice was expressed from a 1000-g sample. Total soluble solids of the juice were determined by Brix refractometry. The remaining fiber cake was dried and ground. Cell wall composition was determined by sequential detergent extraction. Remaining residue was combusted to determine ash content. The commercial and S. officinarum genotypes had higher soluble solids in the juice, and lower fiber content than the S. spontaneum genotypes. The fiber cakes ranged from 91 to 231 g kg-1 solubles, 279 to 339 g kg-1 hemicellulose, 411 to 530 g kg-1 cellulose, 64 to 118 g kg-1 acid-detergent lignin, and 1.5 to 8.5 g kg-1 ash. The amount of soluble material in the fiber cake was higher in the commercial and S. officinarum genotypes. There were significant differences among genotypes in hemicellulose, cellulose and lignin contents, but the differences were not consistent between S. officinarum and S. spontaneum. Differences in ash content were not significant among the genotypes. Reducing lignin content has been suggested as one means of improving lignocellulosic biomass for biofuel production, the natural variability in lignin content among the genotypes suggests that selection for reduced lignin may be possible in sugarcane.