Rice Bran Oil Pressing Process
Rice bran is another major by-product of rice processing besides rice husk, accounting for about 6% of the processed raw grain. Rice bran oil is an oil produced by using rice bran, a by-product of rice processing, as a raw material, and using rice bran oil equipment to process and prepare oil, which can obtain better economic benefits. Rice bran oil is a kind of edible oil with high nutritional value. It is rich in linoleic acid. Regular consumption can reduce the cholesterol content in the human body, which is beneficial to the prevention and treatment of cardiovascular diseases.
Rice bran oil can be extracted from rice bran by using rice bran oil pressing process and rice bran oil leaching process. At present, the rice bran oil pressing process is generally used in rural areas. According to the different rice bran oil pressing equipment used, it is divided into two types: machine pressing and earth pressing. The machine presses oil quickly, with large output and saves labor; the soil press has slow oil output, low output, and takes up a lot of labor, but the equipment is simple and easy to operate. The production of rice bran oil by pressing method is a machine-pressing method that uses a screw oil-pressing mechanism to obtain rice bran oil. Now the rice bran oil pressing process is introduced as follows.
Rice bran oil pressing process:
Rice bran - screening - mixing rice husk - adding water - steaming - frying - pressing - crude bran oil
Rice bran oil pressing process:
① Screening rice bran often contains broken rice and impurities, and broken rice contains a large amount of starch. If it is not removed, the starch will be gelatinized and sticky during steaming, which will affect the oil yield of rice bran oil pressing equipment during rice bran pressing. The purpose of screening is to remove broken rice and impurities in rice bran and ensure the oil yield of rice bran oil press equipment. It can be screened with a small square sieve for separating bran and glutinous rice.
② Mixing 4.5% to 5% of the shell of the rice bran with the husk can increase the hardness of the blank, and the steam can easily pass through when the blank is steamed, and the blank is evenly eaten. After mixing the rice husks, turn it evenly.
③ When adding water for steaming, in order to make it easy to get gas, water should be added appropriately. When the moisture content of rice bran is 11% to 12%, generally add 20% water. Add water evenly and loosen the rice bran.
④The purpose of steaming is to soften the coarse fibers in the rice bran, coagulate the protein, rupture the cells, and gather the small oil droplets into larger oil droplets so that they can be easily squeezed out. One of the methods of steaming the blanks is to put the rice bran with water in the steaming bucket and cook for 40-50 minutes to make the blanks absorb enough water. The steaming temperature should be controlled between 102 and 105 °C. Cook and steam until the moisture of the rice bran reaches 32% to 37%, and at the same time, the color becomes darker, and it feels soft and slightly sticky when squeezed by hand.
⑤ The function of frying blanks is to reduce the moisture of the blanks, so as to facilitate the rice bran to squeeze out the oil. The specific method is: put the steamed blanks into the iron pot for roasting, and each pot is charged with 3.5-5 kg. When frying, use a high heat first, then use a slow fire, the temperature should be between 115 and 120 ℃, and it should be constantly turned so that the billet is heated evenly, so as not to burn. Stir fry for about 20-30 minutes in each pot, so that the moisture content of the billet is reduced to 5% to 7%. If there is oil stains, it will not stick to a group when you pinch it, and it will feel slightly greasy.
⑥ When the pressed material is put into the rice bran oil pressing equipment, the temperature should be kept between 80-90 °C. When the machine is first turned on, the material should be slowly fed. After the pressing chamber is heated, the feeding amount should be gradually increased, and the screw should be screwed in at the same time. When pressing, the slag between the slits of the pressing bar should be mixed into the blank at any time for re-pressing.
