Industrial Methods for Stabilizing and Extracting Rice Bran Oil

The main nutrients in rice bran are protein, fat, and dietary fiber. The protein content in rice bran ranges from 11% to 15%, fat content from 15% to 22%, and dietary fiber content from 24% to 29%. Additionally, rice bran contains small amounts of active components such as oryzanol, sterols, squalene, and tocopherols. Notably, rice bran protein contains all essential amino acids and is hypoallergenic, making it suitable for processing into infant food.

The fatty acid composition of oil extracted from rice bran is quite good. It mainly consists of oleic acid, linoleic acid, stearic acid, palmitic acid, and small amounts of α-linolenic acid and arachidic acid. The ratio of oleic acid to linoleic acid is approximately 1.1:1, which is close to the proportion of fatty acids required by the human body. Additionally, the oil contains numerous lipid accompaniments such as tocopherols, phospholipids, plant sterols, squalene, and oryzanol. Therefore, in many regions, rice bran oil is considered a highly nutritious and healthy oil, comparable to olive oil.

In the past, the utilization rate of rice bran in China was relatively low, with most rice bran used for animal feed. Only about 20% of rice bran was processed into rice bran oil. This is because the lipase in rice bran is activated when the bran is separated from the rice, causing the fat in the bran to decompose rapidly, leading to a quick increase in free fatty acids. Typically, within a week, the free fatty acid content reaches a high proportion.

The oil extracted from such raw materials has a high acid value, is prone to rancidity, and the high free fatty acid content is detrimental to human health. Reducing the acid value to meet the standards for healthy oil requires high processing costs, leading many oil factories to abandon it. This has resulted in the slow development of rice bran oil production and processing in China, with low added value for rice bran. However, with continuous development and the advancement of modern technology, the preservation technology for rice bran oil materials has become increasingly mature.

Various methods such as heat treatment, extrusion, microwave treatment, chemical treatment, and enzyme treatment can be used to maintain the stability of rice bran raw materials. Considering industry scale, production methods, production efficiency, processing costs, and the impact of stabilized rice bran on subsequent processes, extrusion is currently the most widely used industrial method for stabilizing rice bran. Extrusion utilizes the high temperature, high pressure, and high shear force generated during the process to inactivate enzymes such as lipase and peroxidase in rice bran, thereby extending its storage life. Extrusion treatment has little impact on the main fatty acids in rice bran oil, and the production of rice bran oil is progressing in a better direction.

Using rice bran to produce nutritious and healthy rice bran oil can enrich China's edible oil resources and aligns with national policies to vigorously develop the rice bran industry, explore rice bran nutrition, reduce grain loss, and enhance national nutrition and health. Industry practitioners have calculated that if all the rice bran produced annually in China were used for rice bran oil extraction, it could produce 3 million tons of rice bran oil annually, equivalent to a 7% increase in edible oil self-sufficiency, which would be beneficial in reducing dependence on imported edible oil. In recent years, many investors have also focused on rice bran oil processing.

Rice bran oil can be extracted using various methods such as microwave-assisted extraction, ultrasonic-assisted extraction, enzyme-assisted aqueous extraction, supercritical fluid extraction, subcritical water extraction, and solvent extraction. Among these, solvent extraction is currently the most widely used oil extraction process in industrial production. Solvent extraction utilizes the solubility of oil in the selected solvent, soaking the processed oil material in the solvent to dissolve the oil, and then separating the solvent from the crude oil through processes such as distillation. The most commonly used solvent is n-hexane, which is inexpensive, volatile, and efficient. However, considering environmental impact, alternatives such as ethanol, isopropanol, and D-limonene are being explored.

The production of rice bran oil through solvent extraction involves the operation of grain and oil equipment. From the selection, cleaning, and extrusion of rice bran raw materials to solvent extraction, various mechanical equipment is required. Good grain and oil equipment can achieve twice the result with half the effort. Here, we recommend the rice bran oil extraction production line designed and manufactured by Henan Huatai Oil Machinery.