The dewaxing or degreasing process of oils and fats is mainly used to remove waxes, solid lipids and high melting point substances contained in oils and fats to ensure the transparency and fluidity of oils and fats in low temperature environments. This process is essential for some edible oils and industrial oils, especially in cold environments, to prevent the oils and fats from becoming turbid or solidified.
Purpose of oil dewaxing/degreasing
1. Improve appearance:
– Waxes or solid lipids in oils and fats tend to solidify or precipitate at low temperatures, causing the oils and fats to become turbid. Dewaxing or degreasing can improve the transparency and appearance of oils and fats.
2. Improve the stability of oils and fats:
– The presence of lipids and waxes may affect the fluidity and stability of oils and fats. After dewaxing/degreasing, the low-temperature fluidity and stability of oils and fats are improved, which is particularly suitable for the production of high-quality edible oils.
3. Meet market demand:
– In cold areas, oils and fats after dewaxing will not become turbid at low temperatures, which meets the market’s requirements for transparent, high-quality oils and fats, especially high-end olive oil, corn oil and sunflower oil.
Application scenarios of dewaxing/degreasing
– Sunflower oil, corn oil, palm oil and other vegetable oils often contain waxes. Dewaxing can keep these oils clear at low temperatures.
– Some industrial oils, such as lubricating oils, cosmetic oil bases, etc., also need to be dewaxed to maintain their performance and appearance at low temperatures.
Introduction to dewaxing/degreasing process
The dewaxing or degreasing process mainly separates waxes and solid lipids in oils by physical methods such as temperature control and filtration. Commonly used methods are freezing method and solvent method.
1. Freezing method
The freezing method is to lower the temperature of the oil so that the waxes and high-melting-point lipids in the oil crystallize and precipitate at low temperatures, and then remove these solid substances by filtering. This method is often used for dewaxing of vegetable oils.
Process flow:
– Cooling crystallization: First, the pretreated oil is cooled to a low temperature of 5°C~10°C, and waxes and lipids begin to crystallize at low temperatures.
– Constant temperature maintenance: The oil is kept at a constant low temperature for a period of time to ensure that the wax is completely crystallized. The holding time is usually 24 to 48 hours, depending on the type of oil and wax content.
– Filtration separation: The crystallized wax is separated from the oil through the filtration system. Commonly used filtration equipment includes plate and frame filter, vacuum filter, etc.
Advantages:
– The process is relatively simple and suitable for dewaxing of most vegetable oils.
– It will not affect the nutritional content and quality of the oil.
Disadvantages:
– High energy consumption, requiring a long cooling time and a continuous low temperature environment.
– The process efficiency is greatly affected by temperature control, and a longer time and more filtration steps are required when the wax content is high.
2. Solvent method
The solvent method is to add specific solvents (such as acetone, ethanol, etc.) to the oil to dissolve or precipitate the wax in the oil, and then remove the wax through the selective dissolution or extraction of the solvent.
Process flow:
– Mixed solvent: Mix the oil and solvent in a certain proportion, and the selective dissolution of the solvent will separate the wax from the oil.
– Cooling precipitation: The mixed oil is kept at low temperature for a period of time to promote the crystallization or precipitation of the wax.
– Filtration separation: Separate wax from oil by centrifugation or filtration. Then recover the solvent by evaporation, leaving the treated oil.
Advantages:
– High efficiency, especially suitable for oil with high wax content.
– Can complete the dewaxing process quickly, suitable for large-scale industrial production.
Disadvantages:
– Requires a solvent recovery system, which increases equipment investment and operating costs.
– The use of solvents has certain environmental and safety risks.
Introduction to dewaxing/degreasing equipment
1. Frozen dewaxing tank:
– Function: Used to freeze oil and fat so that wax and lipid substances crystallize and precipitate at low temperature.
– Features:
– Equipped with a cooling device to control the temperature of the oil and fat to ensure the dewaxing effect.
– The insulation system can maintain a constant temperature at low temperature to promote complete crystallization of wax.
2. Filter:
– Function: Used to separate crystallized wax and solid lipids in oil and fat.
– Commonly used equipment: plate and frame filter, vacuum filter, centrifuge, etc., which can efficiently separate solid wax from oil and fat.
3. Solvent extraction equipment:
– Function: used for the mixing, extraction and separation of oil and solvent in the solvent dewaxing process.
– Features:
– Equipped with a solvent recycling system to reduce solvent waste and environmental impact.
– Suitable for industrial large-scale production.
Factors affecting the dewaxing/degreasing process
1. Temperature:
– Temperature is a key factor in the dewaxing process. The freezing method requires the temperature to be controlled within a range suitable for wax crystallization, usually between 5°C and 10°C; the solvent method requires precise control of the temperature of the solvent to promote the precipitation of wax.
2. Time:
– Freeze dewaxing requires a longer holding time to ensure that the wax is completely crystallized and precipitated; while the solvent method has a shorter dewaxing time, it still requires sufficient solvent mixing time to achieve the desired effect.
3. Filtration accuracy:
– The accuracy of the filtration equipment has a direct impact on the dewaxing effect. The higher the filtration accuracy, the less residual wax, and the better the transparency and quality of the oil.
Advantages and Challenges of Dewaxing/Degreasing Process
1. Advantages:
– Improve the quality of oils and fats: Dewaxing can significantly improve the transparency and stability of oils and fats, especially in low temperature environments, the oils and fats will not become turbid.
– Wide application: The dewaxing process is applicable to a variety of vegetable oils and industrial oils and fats, especially in cold areas.
– Low temperature storage: Dewaxed oils and fats can still maintain good fluidity and appearance at low temperatures, which meets market demand.
2. Challenges:
– High energy consumption: The freezing method requires long-term low-temperature treatment, which consumes a lot of energy, especially for large-scale production.
– Equipment investment: Dewaxing equipment such as freezing tanks and filters requires high equipment investment, especially solvent dewaxing requires an additional solvent recovery system.
– Operational complexity: The solvent method has high requirements for the operating environment and has certain safety and environmental risks.
By rationally selecting the dewaxing/degreasing process and optimizing the process parameters, oil and fat producers can effectively improve the quality of oils and fats, so that they can still maintain good fluidity and transparency in low temperature environments, and meet the diverse needs of the market.