Journal of the American Oil Chemists' Society

, Volume 89, Issue 7, pp 1345–1353 | Cite as

Ethanol Production from Soybean Fiber, a Co-product of Aqueous Oil Extraction, Using a Soaking in Aqueous Ammonia Pretreatment

  • Bishnu Karki
  • Devin Maurer
  • Shannon Box
  • Tae Hyun Kim
  • Stephanie Jung
Original Paper

Abstract

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.

Keywords

Alkaline pretreatment Ammonia steeping Aqueous extraction Soybeans Soybean fiber Extrusion Ethanol Delignification Lignocellulose Biomass 

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Copyright information

© AOCS 2012

Authors and Affiliations

  • Bishnu Karki
    • 1
  • Devin Maurer
    • 1
  • Shannon Box
    • 1
  • Tae Hyun Kim
    • 2
    • 3
    • 4
  • Stephanie Jung
    • 1
    • 2
  1. 1.Department of Food Science and Human NutritionIowa State UniversityAmesUSA
  2. 2.Center for Crops Utilization Research CenterIowa State UniversityAmesUSA
  3. 3.Department of Agricultural and Biosystems EngineeringIowa State UniversityAmesUSA
  4. 4.Department of Natural Resource Ecology and ManagementIowa State UniversityAmesUSA

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