Why activated clay is critical in edible oil decolorization process?

In the edible oil refining industry, the edible oil decolorization process plays a pivotal role in determining the final product's quality, stability and consumer acceptability. Among various edible oil decolorization methods, activated clay (commonly referred to as bleaching earth) stands out as the most widely used and effective adsorbent. Its importance stems from its unique physicochemical properties, which enable it to remove not only undesirable color pigments but also a range of impurities that affect oil quality. This article will explain to you the reason why activated clay is crucial in the edible oil decolorization process.

1. Has Superior Adsorption Capacity for Pigment Removal

Crude edible oils contain natural pigments such as chlorophyll (imparting green hues) and carotenoids (responsible for yellow to red colors). While some pigments are harmless, others can affect the oil's appearance and stability. Activated clay, with its high surface area (100–300 m²/g) and microporous structure, effectively adsorbs these color bodies. The acid-activated form of clay (typically treated with H₂SO₄ or HCl) further enhances its adsorption efficiency, ensuring the production of light-colored, visually appealing oil that meets market standards.

Activated clay

2. Remove Oxidation Products and Impurities

Beyond pigments, crude edible oils often contain oxidation byproducts (peroxides, aldehydes and ketones) formed during extraction and processing. These compounds contribute to rancidity and off-flavors, significantly reducing shelf life. Activated clay plays a crucial role in adsorbing these oxidation products, thereby improving the edible oil's oxidative stability. Additionally, it removes trace metals (iron, copper) and residual phospholipids, which can catalyze further degradation. This purification step is essential for producing oils with prolonged freshness and minimal taste defects.

3. Enhance Edible Oil Safety and Compliance

Modern food safety regulations impose strict limits on contaminants such as polycyclic aromatic hydrocarbons (PAHs), pesticide residues and soaps remaining after alkali refining. Activated clay acts as a final purification step, trapping these impurities before edible oil deodorization process. This ensures compliance with international standards (e.g., Codex Alimentarius, EU regulations) and minimizes health risks associated with contaminated edible oils.

4. Improve Edible Oil Decolorization Process Efficiency and Cost-Effectiveness

While alternative adsorbents like activated carbon or silica gels exist, activated clay remains the preferred choice due to its optimal balance of performance and cost. Its high adsorption capacity allows for lower usage rates, reducing operational expenses. Moreover, its compatibility with different oil types—palm oil, soybean oil, sunflower oil, canola oil, etc.—makes it a versatile solution for refineries processing multiple oil varieties.

Edible oil refining machine

5. Affect the Final Edible Oil Quality and Marketability

The edible oil decolorization process directly influences consumer perception. Dark or turbid edible oils are often associated with poor quality, while clear, bright oils command higher market value. By ensuring effective pigment and impurity removal, activated clay helps producers achieve premium-grade oils suitable for retail, food manufacturing and export markets. Furthermore, the improved oxidative stability extends shelf life, reducing losses due to spoilage.

Refined edible oils

To sum up, activated clay is indispensable in edible oil refining, serving as the backbone of the edible oil decolorization process. Its multifunctional adsorption capabilities make it irreplaceable for producing safe, stable and high-quality edible oils. As consumer demand for cleaner and longer-lasting edible oils grows, the role of activated clay will only become more critical in meeting industry standards and ensuring product excellence. If you have any questions about the importance of activated clay in edible oil decolorization process or are interested in edible oil refining technology and equipment, please feel free to contact Henan Glory Company. Our professional engineers will answer your questions!