OPTIMIZATION OF ENZYME DOSAGES FOR HYDROLYSIS OF DESTARCHED CORN FIBER SUBJECTED TO ACID AND ALKALINE PRETREATMENTS FOR IMPROVED FERMENTABLE SUGAR YIELD

摘要

Optimization of enzyme dosages for the hydrolysis of acid and alkaline treated destarched corn fiber with the objective of increasing the fermentable sugar yield was investigated using response surface methodology. Destarched corn fiber was pretreated by 0.75 % of sulfuric acid and sodium hydroxide in the autoclave at 121 degrees C for 1 h. The dry solid fraction was used for determining the composition, for characterization (crystallinity index, microstructure), and enzymatic saccharification. The experimental design for enzyme dosage optimization had fifteen combinations with three levels (1, 0, 1) of Celluclast 1.5L, beta-glucosidase and Viscozyme L. When compared to acid pretreated fiber, alkaline treated destarched corn fiber presented significantly decreased lignin content for efficient enzymatic saccharification. The optimum enzyme dosages for alkaline treated destarched corn fiber were as follows: 6.78 and 6.05 FPU/g of Celluclast 1.5L, 28.65 and 30.18 CBU/g of beta-glucosidase, and 2.31 and 0.90 FBG/g of Viscozyme L, which allowed obtaining maximum reducing sugar (316.20 mg/g) and glucose (6.09 mg/g).