In the edible oil processing sector, rice bran oil is highly favored by the market and regarded as a “nutritious and healthy oil” due to its rich content of components such as oryzanol and phytosterols. Solvent extraction has become the mainstream method for the large-scale production of rice bran oil, thanks to its high oil yield and superior efficiency.
Solvent extraction is a process that utilizes the ability of a solvent to dissolve oils and fats, thereby extracting them from the raw material. Rice bran, which has a relatively low oil content and a complex structure, is difficult to process effectively via traditional mechanical pressing; solvent extraction provides an ideal solution to this challenge.
In the solvent extraction of rice bran oil, the cleaned rice bran is first crushed to achieve a uniform particle size, creating optimal conditions for the subsequent extraction stage. The rice bran is then mixed with a specific solvent. Within the extraction equipment, the solvent rapidly penetrates the rice bran cells, dissolving the oil and carrying it out to form a “miscella” (a mixture of oil and solvent). Through repeated extraction, the vast majority of the oil is removed from the rice bran. The resulting “wet meal” undergoes processes such as desolventizing (steaming and stripping) to remove any remaining solvent, while the miscella is subjected to evaporation and stripping to recover the solvent, ultimately yielding pure crude rice bran oil. This process increases oil yield, reduces production costs, and meets the requirements for large-scale industrial production.
Due to its specific physical and chemical properties, rice bran presents several challenges when subjected to direct solvent extraction—such as slow extraction rates, high solvent consumption, and a tendency for the wet meal to retain solvent or form clumps. These issues can be addressed through pretreatment processes, among which extrusion-expansion stands out as a critical step for improving both the extraction rate and the final oil yield.
During the extrusion-expansion process, the rice bran is subjected to the combined effects of high temperature, high pressure, and mechanical shear forces within an extruder. As the material is propelled by the screw, it undergoes continuous compression and shearing, causing a rapid rise in temperature and the swift evaporation of moisture. This process disrupts the cellular structure of the rice bran; the once-tight cellular tissue ruptures, releasing the oil and creating a porous structure that is more easily penetrated by solvents. Simultaneously, the expanded rice bran gains higher density and improved flowability, which facilitates more thorough contact and mixing with the solvent during the extraction process. Furthermore, the quality of the expanded rice bran meal is enhanced—with an optimal degree of protein denaturation—allowing it to be utilized as an ingredient in animal feed, thereby enabling the comprehensive use of resources.
The expansion process significantly boosts the oil yield from rice bran. It not only increases oil recovery and extraction efficiency but also improves the quality of the resulting meal, which is why it is widely applied in rice bran oil extraction projects.
High-temperature steaming and roasting processes are extensively used in industrial production. Depending on the characteristics of the oil-bearing material and the specific processing requirements, these methods can be categorized into techniques such as seed roasting or steaming-and-roasting, each yielding oil with distinct properties. FOTMA MILL designs production line solutions and processing workflows tailored to individual client needs, providing high-quality equipment and professional services. Should you have any requirements for equipment or questions regarding the processing technology, please feel free to reach out for consultation.
Post time: Oct-20-2026