Among the oil crops, soybean is the most important. All countries eat soybean oil, and the world’s annual output of soybean oil reaches more than 15Mt. Soybean oil has a high digestibility (95%) and a high content of fatty acids, as well as vitamin E and vitamin A. The linoleic acid content in soybean oil is high and does not contain cholesterol. Long-term consumption of soybean oil can prevent arteriosclerosis. Therefore, supercritical CO2 fluid extraction of soybean oil has naturally become a research hotspot for experts. Read More: Soybean Oil Wiki
Supercritical CO2 Fluid Extraction Technology of Soybean Oil
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The technological process of using supercritical CO2 fluid to extract soybean oil is soybean→pretreatment→supercritical CO2 fluid extraction-separation→soybean oil.
The best extraction conditions are extraction pressure 55Mpa, extraction temperature of 50℃, CO2 flow 30kg/h, benzene extraction time 150min, and soybean oil yield of 18.3%. In addition, when the thickness of the bean slices is less than 0.25 mm or in powder form, a higher oil yield can be obtained. However, the moisture content of soybean raw materials between 3% and 15% has little effect on extraction.
Characteristics of CO2 soybean oil
The soybean oil obtained by supercritical CO2 fluid extraction has good quality (see Table 1), and does not need to be degummed, which can reduce the oil loss in the degumming process: the content of phosphorus and iron is low, and the oil extracted by hexane needs to be degummed and refined to achieve such a low content. content; defatted soy flakes (or powder) do not have the original grass flavor and the typical bitterness of solvent soybean flour and can be directly used as a good-tasting, high-quality protein food without a protein refining process.
Hexane extraction vs CO2 extraction
| Analysis results | Hexane extracted | CO2 extracted |
| Yield/% | 19.0 | 18.3 |
| Residual oil/% | 0.7 | 2.1 |
| Chromatographic purification loss/% | 1.9 | 0.6 |
| Free fat anti-acid/% | 0.6 | 0.3 |
| Peroxide value/(mol/kg) | <0.1 | <0.1 |
| Unsaponifiable matter/% | 0.6 | 0.7 |
| Iron/(mg/kg) | 1.45 | 0.3 |
| Phosphorus/(mg/kg) | 505 | 45 |
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