Separating Oil from Aqueous Extraction Fractions of Soybean

Center for Crops Utilization Research, Iowa State University, Ames, IA 50011-1061, USA
Journal of Oil & Fat Industries (Impact Factor: 1.62). 08/2007; 84(8):785-792. DOI: 10.1007/s11746-007-1090-0

ABSTRACT Previous research has shown that enzyme-assisted aqueous extraction processing (EAEP) extracts 88–90% of the total soybean
oil from extruded full-fat soy flakes into the aqueous media, which is distributed as cream (oil-in-water emulsion), skim,
and free oil. In the present work, a simple separatory funnel procedure was effective in separating aqueous skim, cream and
free oil fractions allowing mass balances and extraction and recovery efficiencies to be determined. The procedure was used
to separate and compare liquid fractions extracted from full-fat soy flour and extruded full-fat soy flakes. EAEP extracted
more oil from the extruded full-fat soy flakes, and yielded more free oil from the resulting cream compared to unextruded
full-fat soy flour. Dry matter partitioning between fractions was similar for the two procedures. Mean oil droplet sizes in
the cream and skim fractions were larger for EAEP of extruded flakes compared to non-enzymatic AEP of unextruded flour (45
vs. 20μm for cream; 13 vs. 5μm for skim) making the emulsions from EAEP of extruded flakes less stable. All major soy protein
subunits were present in the cream fractions, as well as other fractions, from both processes. The cream could be broken using
phospholipase treatments and 70–80% of total oil in the extruded full-fat flakes was recovered using EAEP and a phospholipase
de-emulsification procedure.

Download full-text


Available from: Buddhi P. Lamsal, Mar 13, 2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The effects of two commercial endoproteases (Protex 6L and Protex 7L, Genencor Division of Danisco, Rochester, NY, USA) on the oil and protein extraction yields from extruded soybean flakes during enzyme-assisted aqueous extraction processing (EAEP) were evaluated. Oil and protein were distributed in three fractions generated by the EAEP: cream+free oil, skim and insolubles. Protex 6L was more effective for extracting free oil, protein and total solids than Protex 7L. Oil and protein extraction yields of 96 and 85%, respectively, were obtained using 0.5% Protex 6L. Enzymatic and pH treatments were evaluated to de-emulsify the oil-rich cream. Cream de-emulsification generated three fractions: free oil, an intermediate residual cream layer and an oil-lean second skim. Total cream de-emulsification was obtained when using 2.5% Protex 6L and pH 4.5. The extrusion treatment was particularly important for reducing trypsin inhibitor activity (TIA) in the protein-rich skim fraction. TIA reductions of 69 and 45% were obtained for EAEP skim (the predominant protein fraction) from extruded flakes and ground flakes, respectively. Protex 6L gave higher degrees of protein hydrolysis (most of the polypeptides being between 1,000 and 10,000Da) than Protex 7L. Raffinose was not detected in the skim, while stachyose was eliminated by α-galactosidase treatment.
    Journal of Oil & Fat Industries 85(10):985-995. DOI:10.1007/s11746-008-1282-2 · 1.62 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Extraction of soybean oil from flaked and extruded soybeans using enzyme-assisted aqueous extraction processing (EAEP) is a promising alternative to conventional hexane extraction. The efficiencies of four proteases releasing oil from extruded material were compared. Protex 51FP, Protex 6L and Protex 7L each extracted 90% of the total oil available while Protex 50FP gave similar extraction yield as the control (without enzyme treatment). During EAEP, however, a stable emulsion forms that must be broken in order to recover free soybean oil. The potential of various proteases and phospholipases to destabilize the emulsion was determined. Two enzymes, a phospholipase A2 (LysoMax) and a protease (Protex 51FP) were selected to determine the effect of enzyme concentration on demulsification. Although at a 2% concentration (w/w, enzyme/(cream+free oil)), each enzyme tested was effective in totally destabilizing the cream; the protease released significantly more free oil than did the phospholipase at concentrations less than 2%. At 0.2% concentration, 88 and 48% of free oil were obtained with the protease and phospholipase, respectively. Reducing the pH of the cream also destabilized the cream with maximum demulsification at the isoelectric point of soy proteins. These results provide destabilization strategies for the oil-rich emulsion formed during aqueous extraction processing of extruded flakes and significantly contribute to the development of this environmentally-friendly technology.
    Bioresource Technology 09/2008; 100(2):527-33. DOI:10.1016/j.biortech.2008.05.057 · 5.04 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A bench-scale aqueous enzymatic method was developed to extract corn oil from corn germ from either a commercial corn dry mill or corn germ from a newly-developed experimental enzymatic wet milling process (E-Germ). With both types of germs, no oil was extracted when acidic cellulase was the only enzyme used. Pre-treating dry milled corn germ by heating it in boiling water or microwave pretreatment, followed by enzymatic extraction with the acidic cellulase resulted in oil yields of about 43% and 57%, respectively. A two-step process, combining both acidic cellulase and alkaline protease treatments, with no heat pretreatment, achieved oil yields of 50-65% from dry milled corn germ and 80-90% from E-Germ.
    Journal of Oil & Fat Industries 05/2009; 86(5). DOI:10.1007/s11746-009-1363-x · 1.62 Impact Factor