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Ethanol Production from Soybean Fiber, a Co‐product of Aqueous Oil Extraction, Using a Soaking in Aqueous Ammonia Pretreatment
Author(s) -
Karki Bishnu,
Maurer Devin,
Box Shan,
Kim Tae Hyun,
Jung Stephanie
Publication year - 2012
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-012-2016-z
Subject(s) - chemistry , cellulase , hydrolysis , ethanol , chromatography , enzymatic hydrolysis , yield (engineering) , extraction (chemistry) , aqueous solution , fermentation , fiber , ammonia , food science , biochemistry , materials science , organic chemistry , metallurgy
The effectiveness of soaking in aqueous ammonia (SAA) as a pretreatment method for the conversion of soybean fiber to ethanol via simultaneous saccharification and fermentation (SSF) was investigated. Insoluble fiber is a co‐product from oil and protein extraction using two‐stage, countercurrent, enzyme‐assisted, aqueous extraction processing of full‐fat soybean flakes (FFSF) and extruded FFSF. The fiber fractions were soaked in 15 wt% aqueous ammonia at 1:10 solid‐to‐liquid ratio. The effects of operating variables, including treatment times (6, 12, and 24 h), treatment temperatures (60 and 80 °C), and cellulase loadings (15 and 60 FPU/g‐glucan) on the degree of enzymatic hydrolysis were determined. The best SAA conditions were 80 °C for 12 h followed by an enzyme loading of 15 FPU/g‐glucan, which produced a 152‐mg/g glucose yield after 48 h of hydrolysis. This was 8.7 times the amount produced from the same fiber not pretreated with SAA. The glucose yield increased to 381 mg/g when fiber obtained from extruded FFSF was submitted to SAA. SAA (80 °C, 12 h) on extruded fiber subjected to SSF increased ethanol yield from 0.06 g of ethanol/g [40% of theoretical yield] (for non SAA pretreated fiber) to 0.25 g of ethanol/g [92% of theoretical yield]. The combination of extrusion and SAA was an efficient means for converting the fiber‐rich soybean fraction into ethanol.