Purifying Frying Oil Performance And Ultrafiltration Dynamics Of Stainless Steel Membrane

A series of chemical reaction will take place in the edible during the process of frying the food in high temperature. As a result, the oil's color becomes dark. Viscosity becomes heavy, peroxide and acid prices rise. These physical and chemical indexes not only influence the fried food in its color, fragrance and flavor and shorten its quality guarantee period, but also influence the hygiene index of the food, even bringing a threat to body health. Remaining particles in oil in the food's frying process become the relying centre and catalyst of the oil inferior reaction which can be get rid of by means of physical fitter so that reaction speed can be greatly reduced and at the same time, harmful effect of the chemical addictive can be avoided. As a result, the oil's quality can be ensured. This text tries to solve oil's depuration problem in the food's frying process using membrane technology.Membrane used in tests is stainless steel metal membrane, which is regarded as granular-bed to study their geometric parameter, such as the specific surface of the metal membrane ultrafiltration; we can find out that it will not exert an influence in the oil's composition. The metal membrane used in tests has higher separation efficiency. The color of the oil after filtrated by the membrane is obviously better than control, but its viscosity changes littlie. Besides, compared with control the peroxide value and acid price of its chemical indexes also improve a little. Through the membrane filtering, the fried oil's quality has been improved and its life cycle has been increased.Study on the membrane's frying efficiency focuses on the influence some factors have on the filtering speed. These factors mainly include temperature, press, filter cake, oil suspend liquid and membrane's character. The experiment of the net membrane and net oil under constant pressure shows that there is a very good linear relation between pressure and flow velocity. Caused by the rising of the temperature, the oil viscosity drops, so that the filtering can be sped up and the flow of membrane increased. Through testing the ultrafiltrationing speed of two membranes with different geometry character under different pressures, we find out that under the same pressure, the average velocity of membrane 1 is more quickly than membrane 2 in the period of high pressure. Determined data and calculated separation efficiency show that compared with membrane 2, membrane 1 has much satisfactory separation efficiency, though its aperture is large. Taking into account both of the ultrafiltration speed and the separation efficiency index, membrane 1 must be a much ideal choice.Different kinds of oil will also exert an influence on the ultrafiltration efficiency. Through testing the soybean salad oil and the palm oil, we find that the palm oil, with a higher melting point, shows higher stickiness under the same temperature. Therefore, high resistance formed in the membrane's ultrafiltration. We've set up mathematics model of membrane ultrafiltration oil after testing and calculating so that we can predict the membrane's ultrafiltration flow in different conditions.The purification and regeneration of the stainless steel membrane can adopt the method of high temperature oxidization.The test indicates that there are some characteristics with this method to regenerate membrane such as being fast, effectual and pollution-free .