Corn germ oil contains a large amount of unsaturated fatty acids needed by the human body, especially linoleic acid, an essential fatty acid that cannot be synthesized by the human body, with content as high as 60%. Linoleic acid has a certain effect on the prevention and auxiliary treatment of heart disease, arteriosclerosis, and diabetes. In addition, corn germ oil is easily absorbed by the skin, can promote skin metabolism, prevent skin aging, has skincare effects, and has great application potential in the cosmetics industry.
The production of corn germ oil started in the United States in 1890, and it began to be refined and supplied to the market as cooking oil and cold vegetable oil in 1911. The production of corn germ oil in China started relatively late, and the current output only accounts for 3% of the world’s total output. If corn germ oil can be fully utilized, my country will be able to produce nearly 500kt of corn germ oil per year, which will be a very huge Potential source of cereal oils.
Traditional extraction method
Corn germ crude oil obtained by traditional pressing or pre-pressing extraction method is dark amber because it contains more lutein and lutein, and contains more non-fat components (mainly sterols, more than 1%) and free lipids. Alcohol (about 1.5%). In addition, the germ obtained by wet degerming has a strong mellow and corny taste, and must be deacidified, decolorized, deodorized, degummed, etc. before it can be eaten. After repeated refining, the unsaturated fatty acids in corn germ oil are oxidized at high temperatures, and the nutrients such as vitamin E and B-carotene are lost.
Process of Extracting Corn Germ Oil with Supercritical CO2 Fluid
The technological process of using supercritical CO2 fluid to extract corn germ oil is corn germ-drying→crushing→supercritical CO2 fluid extraction→separation→corn germ oil.
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CO2 extraction process parameters
The suitable operating parameters are extraction pressure 25~30Mpa, extraction temperature 45℃, and extraction time 3h. At the same time, measures such as reducing the particle size of corn germ raw materials, changing the shape of raw materials, reducing the natural volumetric proportion (relative density) of raw materials, and adopting tray-type charging methods can significantly improve the mass transfer effect and greatly increase the extraction efficiency. Ethanol can also significantly increase extraction efficiency.
CO2 corn germ oil
Comparing the physical and chemical characteristics of corn germ oil obtained by different methods (see Table 1), it can be seen that the corn germ oil obtained by supercritical CO2 fluid extraction has less phosphorus and low color, and degumming and decolorization processes can be omitted in post-treatment. At the same time, through selective separation, most of the free fatty acids can be removed, so that there is a step of deacidification, which is the advantage of the supercritical CO2 fluid extraction method compared with the traditional process. Read More: Soybean Oil Wiki
However, the oxidation stability of corn oil extracted by supercritical CO2 fluid is significantly lower than that of corn oil produced by pressing. This is because the content of oil phospholipids extracted by supercritical CO2 fluid is too low. Phospholipid itself has no anti-oxidation ability, but it is a significant synergist of antioxidant tocopherol. Adding a certain amount of phospholipid to the oil extracted by supercritical CO2 fluid can effectively improve its oxidation stability.
In addition, when the corn germ is just removed, it needs to be dried immediately to kill the enzyme. Otherwise, it will affect the acid value of the germ, and then affect the acid value of germ oil.
| Index | CO2 oil | Pressed Oil Sample |
| Smell, taste | Distinctive smell and taste | Slight smell |
| Transparency | Transparent | Slightly turbid |
| Density | 0.9178 | 0.9291 |
| Refractive index | 1.4735 | 1.4744 |
| Moisture and volatile Matter/% | 0 | 0.075 |
| Impurities | 0 | 0.15 |
| Acid value/(mgKOH/g) | 1.68 | 3.29 |
| Heating experiment 280°C | Oil color unchanged, no precipitate | The oil color turns black, there is a small number of precipitates, and there is a peculiar smell |
| Vitamin E content/(mg/100g) | 240 | 180 |
| Phosphorus/(mg/kg) | 5 | 120 |
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