At present, there are 4 main extraction technology for wheat germ oil processing: supercritical CO2 fluid extraction, traditional solvent extraction, low temperature pressing and subcritical low temperature extraction. But the some of these methods have a lot of shortcomings.
Supercritical CO2 fluid extraction High Cost, Low Output: As its requirements for equipment is very high, supercritical CO2 fluid extraction machine is very expensive. Besides, its output is low and difficult to adapt to large-scale production.
Traditional Solvent Extraction (Hexane) High processing temperature, high energy consumption, low quality of oilcakes or meals. It is a process of extracting oil at normal pressure by use of Hexane. The temperature of extracting process and desolventizing process is high, resulting in high rate of protein degeneration of oilcakes or meals.
Low Temperature Oil Pressing - High residual oil content in oil cakes / meals; high impurities and moisture content. Direct squeezing or expelling is not suitable for low oil yield materials such as wheat germ.
Advantages of Subcritical Extraction Technology
Subcritical Extraction Technology is a kind of pressurized (0.3-0.8 MPa) fluid extraction process. The extracting agent exists in the form of gas under normal pressure, while under critical pressure it exists in the fluid state. Under critical pressure, the molecular diffusion ability of extraction solvent is enhanced, transfer rate is accelerated, permeability and dissolving capacity is improved significantly. Besides, as it is a kind of low temperature extraction technology, the natural active ingredient in extraction materials are fully retained and protected.
The extraction process is cut off from the air, which can avoided oxidation reaction of special materials and help getting high grade oil products just as supercritical extraction. But the extraction pressure is much lower than supercritical extraction, which is a good thing that makes the equipment price is much lower and also make it feasible for industrialization scale production.
