Oil Pressing Section
Oil pressing, sometimes we called expeller pressing is the way for extracting oil from oilseeds. The process of oil pressing by using oil press machine is relatively simple with less supporting oil mill machinery. Only one oil press is needed to finish the oil pressing process. After being pressed by the oil press, it is only necessary to filter and purify the crude edible oil to obtain pure natural edible oil. This method uses pure physical pressing, retains the original taste of the edible oil, so the requirements for the oilseeds are very strict. The edible oil obtained by the oil press machine has a mellow fragrance, rich in various vitamins and no additives. It is a very healthy green food.
Basic Principle Of Oil Extraction
As a kind of important oil mill machinery, when it start pressing, the particles of the pressed material are subjected to strong pressure, resulting in two different changes in the liquid portion and the gel portion, respectively, in which the grease is extruded from the oil void and the extruded particles are elastically deformed hard cake. In this process, the cell bodies of oil seeds are destroyed and the oil is squeezed out of the oil. We commonly used oil press machine is screw oil press.
With the pace of development of oil production and processing technology greatly accelerated, rice bran oil, rapeseed oil, corn germ oil, almond oil, pumpkin seed oil, perilla oil, grape seed oil, special oil sand oil and new varieties of special oil, grease, oil and soy protein deep processing products have been developed and put on the market. In addition to oil pressing, solvent extraction process is another way to get oil from oil seeds. For peanut, rapeseed, sunflower seeds and other high oil content seeds, also can be used to pre extract part of oil, then the rest of the oil use solvent extraction process method, divided into two steps to get oil. The combination of oil pressing and solvent extraction process is an important trend in the edible oil industry.
The Basic Process Of Oil Pressing Technology
1. Conventional process of expeller pressing
Green-pressing→ Steam cooking→Pressing→Filtration→Crude oil
2. Special oil production process
Oilseeds→ Cooking→Pressing→Filtration→ Mellow oil
3. Oil cold expeller pressing production process
Oilseeds→Whole seed cold pressing→Filtration→ Cold pressed oil
Cold Pressing And Hot Pressing
Cold pressing is a kind of expeller pressing way. Cold pressed oil is not heated before the oil pressing, usually below 60 ℃ in the environment, into the cold press oill extraction machine for pressing, nutrient retention remains the most complete. Cold pressed oil from the low temperature, the acid value is low, generally do not need refining, after sedimentation and filtration, the oil can be obtained. Because of the cold pressing oil rate is only half of the hot press method,, so most of the price of cold pressed oil is about 50% higher than the hot oil. Cold pressed oil molecules are not subject to high temperature damage, generally do not need additives, so you can save for a long time. Market value is relatively high. Commonly there are cold pressed peanut oil, camellia oil and so on.
Hot pressing is pressing oilseeds after roasting. Hot pressing out the oil smell mellow, darker, higher yield. Residues left in the product are small and easy to store. Due to the high temperature heat treatment of oil, a series of changes in the oil, resulting in the destruction of oil cells, protein denaturation, reduce oil viscosity, etc. Due to the cold pressed oil without baking, so the smell is poor, but the color is good. From the two methods showed no residual solvent oil. Although the cold pressing is authentic, healthy life choices, but some are not suitable for cold pressed oil. For example, big mouth contains beany flavor, a toxin gossypol cottonseed oil and oil deterioration of aflatoxins, which must be refined to remove. Sesame oil and peanut oil flavor, need to get hot pressing technology. So, cold pressing health, hot pressing delicious.