Separating Oil from Aqueous Extraction Fractions of Soybean

Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011-1061, USA; Center for Crops Utilization Research, Iowa State University, Ames, IA 50011-1061, USA
Journal of Oil & Fat Industries (Impact Factor: 1.59). 01/2007; 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.

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