Rice bran oil has a high starch content and many types of enzymes. It is easy to become rancid and is not suitable for long-term storage. The free fatty acid content of rice bran oil usually obtained from rice bran is about 10%, which makes the loss of rice bran oil refining equipment high during the refining process. In addition, rice bran oil is different from other bulk oils. It contains a certain amount of solid fat of bran wax, which makes the processing process of first-grade rice bran oil more complicated. There are many factors affecting the yield of rice bran oil products, so the yield of high-end rice bran oil products varies greatly, between 40% and 70%.
There are four ways to improve the yield of rice bran oil products:
1. Rice bran pretreatment.. On the one hand, the powdered rice bran can be expanded into a porous columnar structure with good air permeability through puffing treatment, so that the density of rice bran is increased, the penetration speed of solvent is accelerated, and the penetration of solvent is beneficial to the solvent in the leaching process, and the residual oil in rice bran is reduced; on the other hand, the lipase in rice bran can be fully passivated and inactive through puffing treatment, so that rice bran is not easy to rancid during storage, the shelf life of rice bran is extended, the acid value of leached crude oil is greatly reduced, and the quality of rice bran leached crude oil is effectively improved. Therefore, after puffing, rice bran can not only increase the yield, but also improve the leaching characteristics of the material, increase the penetration speed of solvent in the material, save energy in the subsequent processing steps, reduce the solubility of wet meal, increase the concentration of mixed oil, enhance the desolventizing capacity of dewaxing machine and evaporator, reduce various consumption, and increase the oil yield of rice bran.
2. Use solvent dewaxing. According to the average wax content of crude oil of 3.5%, the yield of finished oil dewaxing by solvent dewaxing is 5% higher than that of conventional dewaxing. Conventional dewaxing can improve the dewaxing filtration speed and the finished oil yield by about 1.5% by optimizing the crystallization curve.
3. Use physical refining technology. If the crude oil acid value is 20mg/g. Using physical refining technology, the finished oil yield will be 5% higher than the chemical refining method. At the same time, the finished oil obtained by physical refining is lighter in color and has better quality.
4. Dewaxing and alkali refining in a mixed oil state. The low viscosity of the oil can greatly increase the dewaxing rate. Dewaxing and alkali refining in a mixed oil state can increase the finished oil by about 10%, and the yield of first-grade oil can exceed 70%.
