Soya crude oil is the oil with more impurities obtained through pressing or solvent extraction, which contains more impurities and harmful substances and is not for direct eating. Soybean oil refining can effectively remove the impurities and harmful substances in crude oil to improve the quality and safety of the oil. Depending on the impurities in the soybean oil, the refining of soybean oil is divided into the following steps:
1.Degumming: Impurities in crude oil dissolve in the oil when it is anhydrous, but once hydrated, they can no longer dissolve in the oil, so the use of hydration degumming process with the help of phosphoric acid removes gums (phospholipids and a part of proteins, etc.) from the crude oil, which helps to reduce the turbidity and improve the transparency of the oil.
Soybean oil refining equipment
2.Deacidification: crude oil contains about 0.5 per cent or more of free fatty acids, which have an acidic taste and are sensitive to oxygen, accelerating the oxidative rancidity of fats and oils. Alkaline substances (e.g. sodium hydroxide) are added to the crude oil to neutralise the free fatty acids in it and generate soap feet, which are then separated by methods such as centrifugation or sedimentation, and at the same time, the soap feet adsorption removes additional impurities. This step helps to reduce the acidity and improve the stability of the oil.
3.Decolourisation: Decolourisation is the use of suitable adsorption materials to remove pigments and other impurities such as residual phospholipids, metal ions and oxides, which can increase the antioxidant capacity of the oil and grease, so as to make the oil show a clear and transparent appearance.
4.Deodorization: Removal of substances, such as aldehydes, ketones and other compounds that affect the smell and taste of the oil through processes such as high temperature steam blow-off. This step helps to improve the taste and flavour of the oil.
In addition to the above four steps, the refining process may require other treatments, such as dewaxing (removing the waxy components of the oil), depending on the type and quality of the crude oil. Refined soybean oil has better taste, colour and stability and is more suitable for cooking and consumption.
