Abstract

GONZALEZ-RENTERIA, S.M. et al. Optimization of the enzymatic hydrolysis process of four straw bean varieties (Pinto villa, Pinto saltillo, Pinto mestizo and Flor de mayo). Rev. Mex. Ing. Quím [online]. 2011, vol.10, n.1, pp.17-28. ISSN 1665-2738.

Pinto villa, Pinto Saltillo, Pinto Mestizo and Flor de mayo straw bean varieties were mixed in equal proportions. The mixture chemistry composition was determined and pretreated with NaOH at 0.1, 0.5 and 1.0% for 30, 60 y 90 minutes. The pretreated straw bean was subject to enzymatic hydrolysis for 10 days at 45°C and a pH of 4.5, using a cellulase enzymatic load of 25 UPF/g of cellulose, from a commercial enzymatic concentrate (Celluclast 1.5 L) provided by Novozyme. The produced sugars were determined using the Miller method, and the obtained values used to calculate the hydrolysis yield. The pretreatment and hydrolysis optimal conditions were calculated using the surface response method. The results shown that the straw bean mixture is composed by: 31% of cellulose, 23% of hemicelluloses and 90% of lignin. The pretreatment affects significantly the hydrolysis yield. The maximum saccharification (98.95 ± 8.38%) was obtained with a pretreatment with 0.5% NaOH for 90 minutes at 121°C and hydrolysis for 240h at pH 4.5 and 45°C , using a cellulose enzymatic charge of 25UPF/g of cellulose.

Keywords : optimization; bean straw; enzymatic hydrolysis; pretreatment; cellulose.