Oil deodorization is the last important step in oil refining. The main purpose is to remove odor, volatile substances and other trace undesirable components in the oil to improve the smell, taste and quality of the oil. Through the deodorization process, high-quality, odor-free edible oil can be produced.

Introduction to oil deodorization process

1. Purpose of deodorization:
– Remove odor substances in oil, such as volatile fatty acids, ketones, aldehydes, etc.
– Remove residual free fatty acids and reduce the acid value of oil.
– Remove some pigments and other volatile impurities to improve the transparency and quality stability of oil.
– Increase the storage stability of oil and extend the shelf life.

2. Deodorization principle:
– High-temperature steam distillation: By introducing high-temperature water vapor into the oil, using the principle of distillation, the volatile substances, odor components and residual free fatty acids in the oil are evaporated and discharged through the vacuum system. The addition of steam can promote the evaporation of volatile substances.
– Vacuum conditions: Deodorization under vacuum conditions can effectively reduce the evaporation temperature of volatile substances and reduce the impact of high temperature on the quality of oils and fats.

Oil deodorization process

1. Oil pretreatment:

– Before deodorization, oils and fats need to undergo processes such as degumming, deacidification, and decolorization to remove most impurities. Otherwise, these impurities will produce adverse reactions during the deodorization process and affect the final oil and fat quality.

2. Heating and heating:

– After the oil enters the deodorization tower, it needs to be heated to a high temperature of 220°C~260°C (the specific temperature depends on the type of oil and fat and process requirements). High temperature helps to volatilize bad odors and impurities without causing significant damage to the quality of the oil and fat.

3. Adding steam:

– At high temperature, by spraying high-purity water vapor, the volatile substances and odor components in the oil and fat are taken away by the entrainment effect of steam. These volatile substances are discharged through a vacuum pump and a condenser.
– The amount of steam and the time of introduction should be precisely controlled according to the type of oil and fat, deodorization requirements, etc., and the general introduction time is about 1 to 4 hours.

4. Deodorization under vacuum conditions:

– The deodorization process is usually carried out under high vacuum conditions (vacuum degree is about 0.1~0.5 kPa) to reduce the evaporation temperature of volatile components, prevent the oil and fat from oxidation or thermal decomposition at high temperature, and ensure the deodorization effect and oil and fat quality.

5. Cooling and post-treatment:

– After deodorization, the oil and fat need to be quickly cooled to room temperature to prevent further oxidation of the oil and fat at high temperature. During the cooling process, ensure that the oil and fat are isolated from the air to avoid the occurrence of oxidation reactions.
– The acid value of the oil and fat after deodorization is usually significantly reduced, and the transparency, odor and taste of the oil and fat are greatly improved.

Introduction to oil and fat deodorization equipment

1. Deodorization tower:

– Function: The deodorization tower is the core equipment of the oil and fat deodorization process, which is mainly used to heat the oil and fat and remove volatile substances by steam distillation. There are multiple layers of fillers or spray devices in the tower to ensure that the oil and fat are fully in contact with steam.
– Main features:
– Equipped with a heating system to heat the oil to a specified high temperature.
– A vacuum system ensures deodorization under high vacuum conditions to reduce the risk of oxidation of the oil.
– The packing layer or sprayer can increase the contact area and efficiency between steam and oil to ensure the deodorization effect.

2. Steam generator:

– Function: Used to generate high-purity water vapor to contact with oil during the deodorization process. The purity and temperature of the steam have a direct impact on the deodorization effect, so the steam generator is required to provide constant high-temperature and high-purity steam.
– Main features:
– The output steam temperature can be adjusted to meet the deodorization process requirements of different types of oil.
– The steam purity is high to avoid impurities and moisture from entering the oil and affecting the quality of the oil.

3. Vacuum system:

– Function: The vacuum system is used to maintain a low pressure state inside the deodorization equipment, thereby reducing the evaporation temperature of volatile components and preventing high temperature from damaging the oil.
– Main features:
– The high-efficiency vacuum pump can quickly establish a high vacuum state to ensure that the deodorization process is carried out in a low-pressure environment.
– The system runs stably to ensure constant vacuum degree throughout the deodorization process.

4. Condenser:

– Function: used to condense and recycle steam and volatiles discharged during the deodorization process to prevent them from entering the vacuum system and causing pollution.

– Main features:

– High condensation efficiency to ensure that volatiles and water vapor can be condensed quickly.

– Simple structure and easy maintenance, suitable for large-scale continuous production.

5. Heat exchanger:

– Function: used to quickly cool down the oil after deodorization to prevent the oil from continuing to oxidize or deteriorate at high temperatures.

– Main features:

– Efficient heat exchange design to ensure that the oil can be cooled quickly to ensure its quality.

– Accurate temperature control, suitable for different types of oil treatment.

Factors affecting oil deodorization process

1. Temperature:

– Deodorization temperature is an important factor affecting the deodorization effect. Too low temperature will lead to insufficient evaporation of volatile substances and poor deodorization effect; too high temperature may cause thermal decomposition of oil, affecting quality. Usually the temperature is controlled at 220°C~260°C.

2. Vacuum degree:
– The vacuum degree affects the evaporation temperature and speed of volatile substances. Under high vacuum conditions, volatile substances can be evaporated at a lower temperature, thus avoiding thermal damage to the oil. Usually the vacuum degree is controlled at 0.1~0.5 kPa.

3. Steam volume:
– The amount of steam used and the time of introduction directly affect the deodorization effect. Too little steam will lead to insufficient removal of volatile substances, while too much steam will increase energy consumption and may take away the nutrients in the oil. Therefore, the amount and time of steam should be precisely controlled according to the type of oil and the deodorization requirements.

4. Deodorization time:
– Too short a deodorization time will lead to incomplete removal of volatile substances and poor deodorization effect; too long a time will increase energy consumption and cost, and may have a negative impact on the quality of the oil. Usually, the deodorization time is controlled between 1 and 4 hours.

Advantages and Challenges of Oil Deodorization Process

1. Advantages:
– Remove odor: Through deodorization, odor and volatile substances in oil are effectively removed, improving the smell and taste of oil.
– Reduce acid value: During the deodorization process, the residual free fatty acids are evaporated, which significantly reduces the acid value of oil and improves the stability of oil.
– Improve quality: Deodorization can effectively improve the transparency and purity of oil, making it meet the market requirements for high-quality edible oil.
– Extend the storage period: By removing unstable volatile substances and oxidation products, the deodorization process can extend the shelf life of oil and prevent rancidity.

2. Challenges:
– High temperature risk: The deodorization process needs to be carried out at high temperature. If the temperature is not properly controlled, it may cause thermal decomposition or oxidation of oil, affecting the nutritional content and quality of oil.
– Equipment investment: Deodorization equipment such as deodorization tower, vacuum system and steam generator have large investment, especially in large-scale industrial production, the maintenance and operation costs of equipment are high.
– Energy consumption: The high temperature and vacuum conditions of the deodorization process consume a lot of energy, so how to improve the deodorization efficiency and reduce energy consumption is an important consideration in process design.

By optimizing the oil deodorization process and equipment configuration, the odor and impurities in the oil can be effectively removed, and high-quality edible oil that meets market demand can be produced.