Alkali-explosion pretreatment of straw and bagasse for enzymic hydrolysis
Sugarcane bagasse and wheat straw were subjected to alkali treatment at 200/sup 0/C for 5 minutes and at 3.45 MPa gas pressure (steam and nitrogen), followed by an explosive discharge through a defibrating nozzle, in an attempt to improve the rate and extent of digestibility. The treatment resulted in the solubilization of 40-45% of the components and in the production of a pulp that gave saccharification yields of 80 and 65% in 8 h for bagasse and wheat straw, respectively. By comparison, alkali steaming at 200/sup 0/C (1.72 MPa) for 5 minutes gave saccharification yields of only 58 and 52% in 48 h. The increase in temperature from 140 to 200/sup 0/resulted in a gradual increase in in vitro organic matter digestibility (IVOMD0) for both the substrates. Also, the extent of alkalinity during pretreatment appears to effect the reactivity of the final product towards enzymes. Pretreatment times ranging from 5 to 60 caused a progressive decline in the IVOMD of bagasse and wheat straw by the alkali explosion method and this was accompanied by a progressive decrease in pH values after explosion. In the alkali-steaming method, pretreatment time had no apparent effect with either substrate. An analysis of the alkali-exploded products showed that substantial amounts of hemicellulose and a small proportion of the lignin were solubilized. The percentage crystallinity of the cellulose did not alter in either substrate but there was a substantial reduction in the degree of polymerization. The superiority of the alkali-explosion pretreatment is attributed to the efficacy of fiber separation and disintegration; this increases the surface area and reduces the degree of polymerization. 33 references.
- Research Organization:
- Univ. of Melbourne, Victoria, Australia
- OSTI ID:
- 5260368
- Journal Information:
- Biotechnol. Bioeng.; (United States), Vol. 28:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BAGASSE
ALKALINE HYDROLYSIS
ENZYMATIC HYDROLYSIS
STRAW
CHEMICAL REACTION KINETICS
HYDROXIDES
SACCHARIFICATION
STEAM
SUBSTRATES
SUGAR CANE
WHEAT
AGRICULTURAL WASTES
CEREALS
CHEMICAL REACTIONS
DECOMPOSITION
GRASS
HYDROGEN COMPOUNDS
HYDROLYSIS
KINETICS
LYSIS
ORGANIC WASTES
OXYGEN COMPOUNDS
PLANTS
REACTION KINETICS
SOLVOLYSIS
WASTES
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