Corn germ is a good oil-bearing material in edible oil industry. With the development of corn processing industry such as starch, starch sugar and alcohol in recent years, corn germ oil has increased rapidly in the international market and has become one of the main edible vegetable oil varieties in the world. The main methods to extract oil from corn or maize germ: Screw pressing and solvent extraction.
1.”Screw Oil Pressing / Expelling” is the most used in small to medium scale corn oil manufacturing process. (At present, most corn oil companies or factories use screw pressing process, the oil yield is around 70%.)
Pretreatment and Mechanical Pressing: Screw oil press is generally used. To ensure high oil yield, the pressure of the oil expeller press should be above 69 MPa. After oil pressing, the residual oil in the cake is about 6% ~ 7%, and the water content of oilcake is 3%~4%. For the sake of safety, the water content of the finished cake should be adjusted to about 12%.
Process Flow: Maize Germ → Screening (sieving machine) → Cooking (Roaster) → Oil Expelling (Corn Oil Press Machine) → Filtering (Filter Press) → Refining (Refinery Machine) → Corn Germ Oil
If you are new for corn oil production and just want to start a small scale corn oil manufacturing business with low cost for trail. This equipment set is the best choice for setting up a small scale oil extraction plant.
2.”Prepressing and Solvent Extraction” is more suitable for industrial complete corn oil mill plant. (For large oil mills adopting solvent extraction technology, the corn germ oil extraction rate can reach 98%.)
At present, most corn oil companies or factories use screw pressing process, the oil yield is around 65%~70%, while for large oil mills adopting solvent extraction technology, the corn germ oil extraction rate can reach 98%.
Pretreatment: Drying and Flaking
The water content of maize germ should be controlled in proper range in advance to meet the requirement of pre-pressing and oil extraction processes. It is also conducive to the flaking process and create favorable conditions for reducing the residual oil in meals. The moisture of corn germ after drying should be 10%~11%. The thickness of corn germ after flaking should be controlled between 0.35mm and 0.45mm.
Steaming, Prepressing and Cooling
These can further change the internal and external structure of the corn germ, making the protein solidification, reduce the resistance of oil molecule diffusion and adjust the water and temperature of the germ to be extracted.
Solvent Extraction, Desolvation, Evaporation, Stripping and Solvent Recovery
The process flow of solvent extraction can be divided into: Oil extraction stage, desolventizing and drying of wet meal, evaporation and stripping of mixed oil, condensation and cooling of solvent vapor, recovery of solvent.