Why do you need to steam the embryo before oil extraction?
1. When wetting raw embryos, water penetrates into the interior of intact cells and is absorbed by the gel portion and causes it to swell. The cell membrane is ruptured under the combined effect of heating and mechanical agitation. After the cell membrane rupture, the oil body protoplasm scattered out, thus facilitating the further destruction of cellular organization and the aggregation and separation of oil.
2. Changes of protein
Raw embryo wet, due to a large number of water molecules adsorbed in the protein molecules on the polar base of the formation of hydration membrane, so that the egg expansion, this change makes the dispersed oil and grease aggregation, and promote the integrity of the cell rupture. The high temperature of frying the embryo makes the proteins sex, the denatured proteins condense into a solid state, thus their plasticity decreases and their elasticity rises. Protein structure was broken embryo after its molecules from the regular arrangement of the form into a flexible expansion of the irregular arrangement of the form, so that the original molecules within the hydrophobic group release "out, and hydrophobic combination of fats and oils are also exposed on the surface. The denaturation of protein is very favorable to improve the oil yield, in the process of steaming and stir-frying, protein can also be combined with fat, phospholipids, cotton phenol and sugar, etc. When the steaming and stir-frying temperature is higher (130C), the strong combination of protein and fat and other lipids produced by the reaction is the residual oil in the press cake can not be reduced to a very low level of one of the reasons.
Enzymes in the raw embryo in the steaming and stir-frying process under the action of high temperature, most of the inactivation and passivation, thus providing favorable conditions for the safe storage of oil and cake meal.
3. Changes of oil and fat
When the raw embryo is wet, the action of moisture leads to the expansion of the raw embryo and the mutual aggregation of the raw embryo particles, so that the oil and grease are extruded from the oil protoplasm of the raw embryo and stay on the surface of the raw embryo particles through molecular cohesion. When steaming and stir-frying, due to the increase in temperature caused by the thermal movement of oil molecules to enhance and intermolecular cohesion weakened, resulting in the reduction of viscosity and surface tension of the oil in the raw embryo for the oil to get rid of the adsorption of the hydrophobic group of proteins, to overcome the resistance of the flow of the conditions created. After steaming and stir-frying the embryo, the oil contained therein is gathered into large oil droplets dispersed on the inner and outer surfaces of the embryo, which makes it easier to extract oil by pressing. The oil which is in the form of thin film on the broad surface of the material may be oxidized by contacting with oxygen in the air during heating, resulting in the increase of peroxide value and acid value of the oil.
