Deacidification of Soybean Oil Using Membrane Processing and Subcritical Carbon Dioxide

Abstract

Vegetable oils have been deacidified using supercritical carbon dioxide and membrane processing. However, the pressures required are substantially greater than those used in industry. Therefore, the feasibility of using subcritical carbon dioxide (at much lower pressures) and membrane processing to separate free fatty acids (FFA) from triacylglycerols (TAGs) was examined. First, FFA/TAG solubility tests were completed (10-25°C and 68-136 atm). The oil samples were separated using a FilmTec NF90 or a FilmTec BW30 membrane in a deadend type cell. Within the range examined, the greatest solubility for oleic acid was at 25°C and 136 atm. For soybean oil TAGs, the greatest solubility was at 20°C and 136 atm. However, for the separation of the two components, 20°C and 68 atm was best among the condition combinations examined. The solubility of oleic acid ranged from 0.294 to 0.455 mg/mL in subcritical carbon dioxide, while the solubility of triacylglycerols ranged from 0.066 to 0.139 mg/mL. The FilmTec BW30 membrane provided significantly better separation of FFAs from TAGs than did the NF90 membrane. Both membranes were selective for oleic acid, although the BW30 had greater selectivity for oleic acid (b oleic acid = 2.12, b TAGs = 0.24) than the NF90 membrane (b oleic acid = 1.26, b TAGs = 0.81).

Sub- and supercritical fluid technology applied to food waste processing

“…Both alternatives lead to additional costs, directly related to the need of security equipment, more energy expenses, and other separation procedures needed for environmentally reasons, and also to degradation of the product. In this sense, a new crossflow filtration process was proposed, taking advantage of the low viscosity and superficial tension of supercritical CO 2 [123,126,127]. Indeed, this process increases the quality of the product and is environment friendly.…”

Application of supercritical fluid extraction for separation of nutraceuticals and other phytochemicals from plant material

“…In order to avoid hydrolysis, chemical and physical deacidification methods have been used in the industry. Some processes of deacidification could be performed by SFE [179,302,303]. When oils are removed from a solid material, extraction is usually semicontinuous.…”

State of art of the application of membrane technology to vegetable oils: A review

“…In a combined process using refined soybean oil (triacylglycerols source) and oleic fatty acid as feed in a filtration process through reverse osmosis and nanofiltration membranes, combined with extraction by sub-critical pressurized fluid carbon dioxide, Lai, Soheili, and Artz (2008) obtained the preferential permeation of oleic acid in relation to the triacylglycerols. As from a model system containing 40% oleic acid and 60% triacylglycerols (w/w), permeation through the reverse osmosis membrane (BW 30) resulted in a permeate containing more than 80% w/w in oleic acid, whilst permeation through the nanofiltration membrane (NF 90,MWCO 200 Da) resulted in a permeate with approximately 50% w/w oleic acid.…”