Efficiency of pretreatments for optimal enzymatic saccharification of soybean fiber

Abstract

The effectiveness of several pretreatments [high-power ultrasound, sulfuric acid (H(2)SO(4)), sodium hydroxide (NaOH), and ammonium hydroxide (NH(3)OH)] to enhance glucose production from insoluble fractions recovered from enzyme-assisted aqueous extraction processing of extruded full-fat soybean flakes (FFSF) was investigated. Sonication of the insoluble fraction at 144 μm(pp (peak-to-peak)) for 30 and 60s did not improve the saccharification yield. The solid fractions recovered after pretreatment with H(2)SO(4) [1% (w/w), 90°C, 1.5h], NaOH [15% (w/w), 65°C, 17 h], and NH(3)OH [15% (w/w), 65°C, 17 h] showed significant lignin degradation, i.e., 81.9%, 71.2%, and 75.4%, respectively, when compared to the control (7.4%). NH(3)OH pretreatment resulted in the highest saccharification yield (63%) after 48 h of enzymatic saccharification. A treatment combining the extraction and saccharification steps and applied directly to the extruded FFSF, where oil extraction yield and saccharification yield reached 98% and 43%, respectively, was identified.