Why Do I Need To Steam The Embryo Before Pressing Oil? Oil Press Machine Manufacturers For You To Answer
Steamed and stir-fried embryo
The process of transforming raw embryo into cooked embryo through wetting, steaming, frying, etc., is called steaming and frying (or tempering). Steaming and stir-frying is a very important process in the production of oil extraction.
1. Purpose and type of steaming
The purpose of steaming is to change the micro-ecology, chemical composition and physical state of the embryo through the action of temperature and water, so as to increase the extraction rate of oil and improve the quality of oil and cake. Steaming and stir-frying can completely break the embryo of the oil cells, denature the protein, reduce the oil, oil viscosity and surface tension, adjust the elasticity and plasticity of the embryo, and passivate enzymes.
The types of steamed stir-frying can be divided into dry steamed stir-frying and wet steamed stir-frying.
2. Dry steaming and stir-frying only heat and dry the seed or oil seed, not wet it. This steaming method is only used for the steaming of oil, such as the frying of sesame seeds when making small ground sesame oil, the frying of peanut kernel when making Luzhou-scented flower oil, and the frying of cocoa seeds when extracting oil from cocoa seeds.3. Wet steaming means that at the beginning of steaming, water is added or direct steam is sprayed into the raw embryo to achieve the initial steaming water, and then the wet embryo is steamed and stir-fried, so that the moisture, temperature and structure of the cooked
When the embryo is wet, a large number of water molecules adsorb to the polar groups of protein molecules to form a hydration film, which causes the egg to expand, and this change causes the dispersed oil and promotes the intact cell to break up. The high temperature of stir-fried embryo makes the protein and the denatured protein condense into a solid state, so its plasticity decreases and elasticity increases. After the protein structure is broken, its molecules change from a regular arrangement form to a flexible and irregular arrangement form, so that the hydrophobic group inside the original molecule is released, and the oil bound with the hydrophobic group is also exposed to the surface. The denaturation of protein is very beneficial to improve the oil yield. During the steaming and stir-frying process, protein can also combine with fats, phospholipids, gossypol and sugars, etc. When the steaming and stir-frying temperature is high (130C), the strong binding reaction between protein and fats and other lipids is one of the reasons why the residual oil in the pressed cake cannot be reduced very low.
Most enzymes in raw embryos are deactivated and passivated under the action of high temperature in the process of steaming and frying, which provides favorable conditions for the safe storage of oil and cake.
3. Changes in grease
When the embryo is wet, due to the action of water, the embryo expands and the embryo particles interact with each other, so that the oil is extruded from the oil protoplasm of the embryo and stays on the surface of the embryo particles through molecular cohesion. During steaming and stir-frying, due to the increase of temperature, the thermal motion of oil molecules is enhanced and the cohesion between molecules is weakened, which leads to the decrease of the viscosity and surface tension of oil in the raw embryo, creating conditions for oil to get rid of the adsorption force of protein hydrophobic groups and overcome the resistance of flow. After steaming, the oil contained in the embryo is dispersed in large oil droplets on the inner and outer surfaces of the embryo, making it easier to extract oil from the press. When the grease is in the shape of film on the wide surface of the material, the contact with oxygen in the air may lead to oxidation, resulting in the increase of the peroxide value and acid value of the grease.
