The acid value of edible oils is one of the most critical indicators of their quality and stability. It directly affects the oil’s taste, shelf life, and food safety. The acid value primarily stems from free fatty acids (FFAs) naturally present in oilseeds, as well as those generated through hydrolysis during oil processing and storage.
To reduce the acid value of the finished oil, the deacidification process in edible oil refining plays a decisive role. This process uses chemical or physical methods to remove free fatty acids, ensuring product quality meets standards and extending shelf life. The importance of deacidification is reflected in three key aspects: stability, safety, and economic value.
Main Deacidification Methods in Edible Oil Refining
Chemical Deacidification (Alkali Refining)
Chemical refining, also known as alkali refining, is one of the most widely used deacidification methods in the edible oil industry.
Working Principle
Alkaline solution is added to crude oil to neutralize free fatty acids, producing soapstock that can be separated by centrifuges.
Advantages
- Mature and reliable technology
- Suitable for various edible oils
- Can simultaneously remove phospholipids, pigments, and impurities
- Lower equipment investment
Applications
Chemical deacidification is commonly used in:
- Soybean oil refining
- Peanut oil refining
- Rapeseed oil refining
- Cottonseed oil refining
Key Process Parameters
To achieve efficient refining performance, the following parameters must be carefully controlled:
- Alkali concentration
- Reaction temperature
- Mixing intensity
- Retention time
- Centrifugal separation efficiency
Excessive alkali addition may cause neutral oil loss and reduced oil yield, while insufficient alkali leads to incomplete deacidification.
Physical Deacidification (Steam Distillation)
Physical refining removes free fatty acids through high-temperature steam stripping under deep vacuum conditions.
Working Principle
Under temperatures of approximately 250–270°C and vacuum conditions of 1–2 mbar, free fatty acids are separated from triglycerides based on boiling point differences.
Advantages
- Lower oil loss (typically 0.1–0.3%)
- No soapstock wastewater
- High deacidification efficiency
- More environmentally friendly
- Better operating economy for large-scale production
Applications
Physical refining is particularly suitable for:
- Palm oil refining
- Rice bran oil refining
- Animal fat refining
- High-acid-value oils
- Low-phospholipid crude oils
Technical Requirements
Physical refining requires advanced oil refining equipment, including:
- Deacidification towers
- High-vacuum systems
- Steam stripping systems
- Precise temperature control systems
- Efficient heat exchangers
Proper pretreatment such as degumming and bleaching is essential before physical refining.
Key Factors Affecting Deacidification Efficiency
- Temperature Control
Excessively high temperatures can destroy heat-sensitive nutrients and accelerate oil oxidation, while excessively low temperatures reduce the efficiency of free fatty acid (FFA) removal. - Vacuum Stability
Stable deep vacuum conditions improve steam stripping efficiency and minimize the impact of thermal damage on oil quality. - Steam Distribution
Uniform steam distribution ensures thorough contact with the oil and improves mass transfer efficiency. - Equipment Design
Advanced edible oil refining equipment enhances refining efficiency, reduces energy consumption, and minimizes oil loss.
Benefits of Efficient Deacidification
- Extended Shelf Life
Removing free fatty acids significantly slows oxidation and rancidity, helping refined oils maintain freshness during transportation and storage. - Higher Refining Yield
Optimized refining parameters reduce neutral oil loss and increase overall production profitability. - Enhanced Food Safety
High-efficiency acid neutralization removes harmful substances that may irritate the digestive system and reduces smoke generated during cooking. - Strengthened Market Competitiveness
High-quality refined oil with low acid value, clear appearance, and consistent quality is more competitive in the international edible oil market.
Why Choose Huatai Oil Refining Equipment?
With over 38 years of experience in edible oil refining and oil mill plant engineering, Huatai provides advanced refining equipment and customized turnkey engineering solutions to customers in more than 70 countries worldwide.
Huatai’s advanced deacidification towers utilize high-quality 316L corrugated packing to achieve efficient mass transfer, a compact design, and ultra-low residual free fatty acid levels (<0.05%) . A precise vacuum control system (1–2 mbar) and optimized steam distribution technology ensure thorough removal of free fatty acids while minimizing oil loss and preserving valuable nutrients such as tocopherols and sterols.
Whether for small-scale edible oil processing or large-scale industrial refining projects, Huatai provides reliable solutions to help customers achieve high refining efficiency and produce high-quality oil products.