The content of free fatty acid in rice bran oil is too high, will cause the oil to produce the irritating odor, in the refining process the main purpose of oil and fat deacidification is to take off the free fatty acid, the deacidification is one of the key processes in the refining process of rice bran oil, the deacidification method which is usually used has the following three kinds.
1.Physical deacidification method
Physical distillation deacidification is based on the relative volatility of free fatty acids is lower than the characteristics of the oil, the use of steam will be in the oil of free fatty acids and other low molecular volatiles out.
2.Alkali refining deacidification
Alkali refining deacidification, also known as chemical deacidification, is the addition of lye to neutralize the free fatty acids to generate soap, and then centrifuged to remove the soap foot.
3.Esterification deacidification
Esterification refers to the use of catalysts to make the free fatty acids in fats and oils and glycerol, glycerol monoester or di-glycerol ester esterification reaction, the generation of triglycerides. Esterification deacidification has a large application prospect in the refining of high acid value fats and oils, but due to the cost of the process, it has not been widely used.
At present, the main method of rice bran oil deacidification is: alkali refining deacidification. But in the actual production practice found, in the alkali refining deacidification process, the rice bran oil in the cereal vitexin loss is serious, as high as 60%. Analyze the molecular structure and the molecular polarity of the cereal vitexin to find, its molecular structure has the nature of the phenolic class, is weakly acidic. In the process of alkali refining, when the content of FFA in oil and grease decreases constantly, the gluten will also be salted by alkali, the lipophilicity decreases and the hydrophilicity enhances, and the saponified gluten will be adsorbed by the alkaline soap foot in the form of sodium salt, which will lead to the content of gluten to be reduced greatly.
So for the high acid value comparatively high rice bran oil, alkali refining deacidification way is not too cost-effective, need many kinds of ways to combine. In order to avoid the acid value is too high, the processing of the rice bran in advance is more important, the pretreatment and the oil extraction process processing is better, the later refining will be more simple, the quality of the rice bran oil as a whole has a big influence.
SIWEI company has professional rice bran expander can prolong fresh rice bran's preservation time from 24 hours to 30 days, effectively solves the problem that fresh rice bran is difficult to preserve.
In conclusion, the acid value of rice bran oil is high, must use suitable deacidification method and appropriate equipment to remove free fatty acid, in order to reach the level of consumer acceptance.
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