Rice Bran Oil Production Methods: A Comparison of Pressing and Extraction

Rice bran oil is extracted from the by-products of rice processing—rice bran. It contains significantly higher levels of γ-oryzanol, phytosterols, and vitamin E compared to other edible oils. With a light taste and clear color, it is a nutritious and healthy cooking oil.

Rice bran oil can be produced using the pressing method or the extraction method. However, due to the presence of active enzymes and impurities in crude oil, both raw materials and crude oil can quickly acidify. Therefore, timely processing of raw materials and crude oil is necessary to maintain quality.

Rice bran has a low oil content, and the pressing process yields low extraction efficiency and small output. In contrast, the extraction process, particularly the one-step extraction method, efficiently extracts oil from rice bran and reduces the residual oil in the extraction meal to a very low level. It ensures high production efficiency and oil yield. Consequently, larger oil factories often choose extraction equipment and processes for producing rice bran oil.

The steps of the rice bran oil extraction production line mainly include:

Pretreatment: 

The raw rice bran undergoes pretreatment, including separation to remove impurities like broken rice and coarse bran husks. Then, rice bran is conditioned to adjust temperature and moisture, making it suitable for puffing. Puffing disrupts the cellular structure of rice bran, alters its porosity, and enhances its permeability, improving the extraction efficiency.

Extraction:

The pretreated rice bran is transported to the rice bran oil extraction equipment. Using the principle of organic solvent extraction, techniques like spraying and soaking allow solvents to fully contact the rice bran cake, extracting oils and producing miscella.

Desolventization of Wet Meal:

In the desolventization system, evaporation and stripping processes remove solvents from wet meal, recovering the solvents and obtaining desolventized rice bran meal.

Miscella Treatment:

In the miscella processing system, differences in boiling points between oils and solvents are utilized to perform evaporation and stripping, separating the solvent and oil, resulting in crude rice bran oil.

Solvent Recovery:

The solvent recovery system recycles the organic solvent used during extraction, enabling reuse, reducing production costs, and minimizing environmental impact.

It is important to note that crude rice bran oil produced via the extraction process contains impurities like meal powder, plant fibers, phospholipids, free fatty acids, pigments, moisture, and solvents. These impurities can affect the oil's quality and may lead to rancidity. Therefore, crude rice bran oil must undergo refining processes—such as degumming, deacidification, dehydration, decolorization, deodorization, and dewaxing—to remove impurities and harmful elements, making it safe and suitable for consumption.