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Comparative study of the quality characteristics of defatted soy flour treated by supercritical carbon dioxide and organic solvent

Kang, Sung-Won, Rahman, M. Shafiur, Kim, Ah-Na, Lee, Kyo-Yeon, Park, Chan-Yang, Kerr, William L., Choi, Sung-Gil
Journal of food science and technology 2017 v.54 no.8 pp. 2485-2493
absorption, amino acids, carbon dioxide, denaturation, dietary protein, emulsifying, foaming capacity, high protein foods, isoflavones, nutritive value, oils, polyacrylamide gel electrophoresis, protein content, protein denaturation, solvents, soy flour, temperature, total soluble solids
Defatted soy flour is a potential source of food protein, amino acids, ash and isoflavones. The supercritical carbon dioxide (SC-CO₂) and a traditional organic solvent extraction methods were used to remove fat from soy flour, and the quality characteristics of a control soy flour (CSF), defatted soy flour by SC-CO₂ (DSFSC-CO₂) and defatted soy flour by an organic solvent (DSF-OS) were compared. The SC-CO₂ process was carried out at a constant temperature of 45 °C, and a pressure of 40 MPa for 3 h with a CO₂ flow rate of 30 g/min. The DSFSC-CO₂ had significantly higher protein, ash, and amino acids content than CSF and DSF-OS. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis demonstrated that CSF and DSFSC-CO₂ had protein bands of similar intensity and area that indicated no denaturation of protein, whereas DSF-OS showed diffuse bands or no bands due to protein denaturation. In addition to higher nutritional value and protein contents, DSFSC-CO₂ showed superior functional properties in terms of total soluble solids content, water and oil absorption, emulsifying and foaming capacity. The SC-CO₂ method offers a nutritionally and environmentally friendly alternative extraction processing approach for the removal of oil from high-protein food sources. It has a great potential for producing high-protein fat-free, and low-calorie content diet than the traditional organic solvent extraction method.