Abstract
We estimated the effect of residual lignin and pulp swelling on the rate of enzymatic saccharification to increase production of ethanol from acid sulfite pulp (SP) by means of enzymatic treatment. The resolution ratio of hardwood (Acacia mearnsii) SP after the enzymatic treatment was lower compared to softwood (Larix leptolepis) SP even though lignin content of hardwood SP was lower. The pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) analysis revealed that the residual lignin in hardwood SP could more easily adsorb enzyme compared to softwood SP, and the residual lignin in hardwood SP should interfere with the binding of the enzyme to cellulose. The beating treatment of pulp increased the swelling of pulp. The enzymatic saccharification rate was increased by the beating treatment. On the other hand, the delignification treatment was more effective than the beating treatment at enhancing enzymatic saccharification of both hardwood and softwood SPs. We found that the delignification process should be considered a high-priority technique for enhancing enzymatic saccharification of SP.
Highlights
The wood refinery process, which creates fuels and chemicals by utilizing wood, has attracted increasing attention
It is well known that the residual lignin inhibits enzymatic saccharification of pulp because lignin ties up the enzyme to hydrolyze carbohydrates
The resolution ratio of acacia sulfite pulp (SP) caused by the enzymatic treatment was 46.7%, which was lower compared to larch SP, even though the lignin content of acacia SP was lower than that of larch SP
Summary
The wood refinery process, which creates fuels and chemicals by utilizing wood, has attracted increasing attention. The lignin from the enzyme-treated EFB pulp was further purified by washing and they reported that the amount of enzyme adsorbed onto the lignin in the pulp analyzed by Py-GC/MS was decreased by the purification [7]. These results indicated the impurity compounds were removed from the enzyme-treated pulp, and it has been strongly suggested that the ion peaks with m/z = 117 and 130 were derived from the enzyme, not from other compounds. We have reported that the amount of enzyme adsorbed onto residual lignin in larch SP was lower than that in larch soda–AQ pulp [9]
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