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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Functional Foods Research » Research » Publications at this Location » Publication #324321

Research Project: Evaluation of the Chemical and Physical Properties of Low-Value Agricultural Crops and Products to Enhance Their Use and Value

Location: Functional Foods Research

Title: Counter-current carbon dioxide extraction of fat from soy skim

item SOLANA, MIRIAM - University Of Padua
item Teel, Jeffrey
item Hojilla-Evangelista, Milagros - Mila
item BERTUCCO, A - University Of Padua
item Eller, Fred

Submitted to: Journal of Supercritical Fluids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2016
Publication Date: 6/23/2016
Publication URL:
Citation: Solana, M., Teel, J., Hojilla-Evangelista, M., Bertucco, A., Eller, F. 2016. Counter-current carbon dioxide extraction of fat from soy skim. The Journal of Supercritical Fluids. 113:106-111.

Interpretive Summary: This research studied the use of counter-current carbon dioxide extraction as a means to remove lipids from the residual aqueous mixture (i.e., soy skim) resulting from the extraction of soybeans with water. Several factors which could influence the separation were studied, including liquid and supercritical carbon dioxide, solvent-to-feed ratio, ethanol as a modifier and internal column packing. The effects of these factors on lipid removal, protein recovery, protein solubility and protein structure were measured after the extraction. Total fat was reduced from 4.4 in the feed to 0.7% in the raffinate. Protein content, as well as protein structure were essentially unaffected by any of the treatments. Protein solubility was increased significantly between pH 2 and 10 after exposure to the high pressure carbon dioxide. The results obtained in this study demonstrate the potential of counter-current CO2 fractionation as an alternative method to remove residual lipids from soy skim. In addition, our results provide a means to increase the solubility of soybean proteins.

Technical Abstract: This research aims to investigate the use of counter-current carbon dioxide extraction method as a means to reduce residual fat in soy skim after the enzyme-assisted aqueous extraction of soybeans. Extractions with liquid CO2 at 25°C and 10.34 MPa and supercritical CO2 at 50°C and 25.16 MPa are compared. The effects of solvent-to-feed ratio (2.5-10), addition of ethanol as a modifier (5% w/w) and introduction of packing in the column are also analyzed. Results show that the highest reduction of fat content is obtained without modifier and with packing in the column at 50°C and 25.16 MPa. At these conditions, the total fat content present in soy skim was reduced from 4.4 to 0.7%, with the protein content practically unaffected. ANOVA was applied to determine effects on fat and protein in soy skim, being the addition of packing in the column the most significant one. The fatty acid profile was also analyzed, with C18:2 being the predominant fatty acid present in all the soy skim samples. Gel electrophoresis indicated that supercritical CO2 settings did not affect the polyppeptide band patterns; however, higher pressure, temperature, and CO2 flow significantly increased protein solubility in aqueous media (pH 2-10) compared with un-treated samples.