Rice bran oil is a kind of healthy oil rich in gluten, the crude oil contains more complicated and more quantity of oil-soluble substances than other vegetable fats and oils, which makes it difficult to refine rice bran oil, and the loss of neutral oil in the refining process is serious.
The colloidal impurity contained in rice bran oil is mainly hydrated phospholipids and non-hydrated phospholipids, it is difficult to take off cleanly, these colloidal soluble substances not only affect the stability and quality of oil and grease, but also affect the subsequent refining process, the refining degumming is the beginning of the whole edible oil refining plant, the degumming is good or bad will directly affect the subsequent processing. Therefore, degumming process is necessary.
At present, the most used method in the market is hydration degumming, because the cost of this method is lower, or the combination of hydration degumming and acid degumming, the specific operation needs to be adjusted according to the quality of the oil.
Hydration degumming is the use of phospholipids and other colloidal impurities of hydrophilicity, a certain amount of hot water or dilute alkali, salt water solution, phosphoric acid and other electrolytes in water solution, under the stirring added to a certain temperature of the crude oil, so that the colloidal impurities in which the formation of gum clusters, cohesion and sedimentation, after centrifugal separation process, to achieve the removal of colloidal impurities of a kind of degumming method.
In the process of hydrochemical degumming, the insoluble substances are separated out, mainly phospholipids, as well as proteins, glycosylglycerides, mucilage and metal ions, etc, which are combined with phospholipids.
Acid method degumming of rice bran oil is the form of degumming commonly used in factory at present, acid method degumming is by adding acid electrolyte, such as phosphoric acid, citric acid, oxalic acid and so on, make the non-hydration phospholipids in the gross oil turn to hydration phospholipids, make the phospholipids absorb water and swell by adding water, so as to take off the phospholipids. However, because oxalic acid is toxic, from the perspective of food safety and the impact on the physicochemical indicators of by-product phospholipids, the use of food-grade phosphoric acid and citric acid is better. However, in the process of degumming, phosphoric acid acid acid to make part of the pigment acidolysis, the formation of dark flocs, the phospholipids appeared to be denatured, losing some of the physical properties and nutritional functions. Therefore, citric acid is more suitable for degumming.
