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Poster Presentation 1-22
Enzymatic Hydrolysis of Ammonia-treated Rice Straw
B. Sulbarán-de-Ferrer1 , M. Aristiguieta1, B.E. Dale2 and A. Ferrer1
1Dept. of Chemistry, Science Faculty, University of Zulia, Av. Universidad. Grano de Oro. Módulo 2, Maracaibo, Venezuela,
2Dept. of Chemical Engineering, Michigan State Univ., East Lansing, MI
Telephone/fax: 58-261-7414745; E-mail: aferrer1@cantv.net
Rice straw pretreated with liquid anhydrous ammonia was hydrolyzed with cellulase (Spezyme CP, 5 IU/g DM), cellobiase (Novozym 188, 28.4 CBU/g) and hemicellulase (Bio-feed Plus, 2.5 mg/g) at 5% solids for 48 h at 50°C. Ammonia processing conditions were: 1.5 g NH3/g dry matter, 85°C and sample moisture contents of 15%, 35% and 60%. There were four ammonia addition time (min)-processing time (min) combinations: 1-0, 4-0, 1-4 and 4-20. Sugars produced were analyzed as reducing sugars (DNS method) and by HPLC. The production of reducing sugars increased from 10% in the non-treated rice straw to 67% of theoretical in the treated one. Monosaccharide production was greater at higher moisture content and was processing time-dependent. The optimal processing condition was 60% moisture content and a 4-5 min combination. Glucose was the monosaccharide produced in greater amounts, 61%, followed by xylose, arabinose and fructose with 32%, 4%, and 2%, respectively. A combination of high moisture content (60%) and long processing time (20 min) significantly decreased glucose production (p<0.05), while it did not affect xylose production. High sugar yields with relatively low enzyme loadings make ammonia-treated rice straw a potential source of sugars for several purposes, including chemicals and feeds.
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