About Low Free Acid Bleaching Earth
Low Free Acid Bleaching Earth is an activated clay in which residual acidity is reduced after activation. It is intended for oils and fats where the acidity of a conventional bleaching clay causes problems, such as a rise in free fatty acids, acid-catalysed isomerisation, or off-flavour development in delicate products.
Typical users include refiners of specialty oils and blends, oils destined for minimal further processing, and producers who bleach rice bran, coconut, sesame or other oils where flavour, colour and acid value must stay within narrow limits. The grade is also useful for refiners who want to reduce the acidity carried into spent clay and filter equipment. It still provides useful adsorption of pigments, soap traces and metals, although very dark crudes may need a higher dosage than with a more strongly activated clay.
Obsidian Minerals produces Low Free Acid Bleaching Earth in Gujarat, with free acidity, pH, moisture and particle size tested on each batch in an NABL-accredited laboratory. Every shipment includes an SDS, Technical Data Sheet and Certificate of Analysis. Because acceptance criteria for specialty oils vary widely, we recommend a comparative laboratory bleaching test on your oil, and refiners should verify suitability against the regulations in their market.
Typical specifications
| Parameter | Typical Value | Test Method |
|---|---|---|
| Free acidity | ≤ 0.5 mg KOH/g | Internal method |
| pH (10 % slurry) | 4.5–6.5 | Internal method |
| Specific surface area (BET) | 180–240 m²/g | BET, nitrogen adsorption |
| Moisture | ≤ 12 % | Loss on drying, 105 °C |
| Passing 75 µm | 70–85 % | Wet sieve |
| Bulk density | 0.55–0.75 g/cm³ | Internal method |
Typical values for guidance. Guaranteed limits are stated on the Technical Data Sheet and batch CoA. Customers should confirm performance on their own oil by laboratory trial.
Key features & benefits
Low residual acidity
Low Free Acid Bleaching Earth carries far less free acid than conventional activated clays, limiting free fatty acid rise and acid-catalysed reactions in oils that are sensitive to them.
Protects flavour and stability
By reducing acid-driven side reactions during bleaching, the grade helps specialty oils keep their natural flavour profile and supports oxidative stability in finished, packed products.
Gentler on equipment
Lower acidity in the clay and spent cake reduces the acid load on bleachers, filters and cake-handling equipment, which can be a consideration for plants with older carbon steel systems.
Retains useful adsorption
The grade still adsorbs pigments, soap traces and metal ions, so refiners gain lower acidity without giving up the basic purification role of an activated bleaching clay.
Applications
Specialty and flavour-sensitive oils
Used for oils such as sesame, coconut and specialty blends where acid value, flavour and colour must stay within narrow limits and only mild bleaching conditions are acceptable.
Rice bran oil refining
Applied where rice bran oil refiners want to limit acidity added at the bleaching stage, as part of an overall process designed to manage free fatty acids and colour.
Fats for further processing
Suitable for bleaching fats and oils that go on to hydrogenation, interesterification or fractionation, where acid residues could affect nickel catalysts or downstream product quality.
Usage & handling
- Typical dosage: 0.5–2.5 % of oil weight, usually slightly higher than a strongly activated clay for the same colour target.
- Use standard vacuum bleaching conditions, with contact temperature kept as low as practical for heat-sensitive oils.
- Compare acid value before and after bleaching in laboratory trials to confirm the benefit.
- Store sealed in a dry place to protect activity and filtration properties.
Packaging & supply
- 25 kg or 50 kg HDPE or paper bags
- 1 MT or 1.2 MT jumbo (FIBC) bags
- Private-label and custom packaging on request
Frequently asked questions
Why use a low free acid bleaching earth?
Conventional activated clays contain residual acid that can raise free fatty acids, promote isomerisation and affect flavour in sensitive oils. A low free acid grade reduces these effects while still adsorbing pigments and impurities. It is chosen when acid value and flavour matter more than achieving the lowest possible clay dosage.
Will I need a higher dosage than with standard bleaching earth?
Often slightly higher, because lower acidity usually comes with somewhat lower activity on heavy pigments. The difference depends on the oil. A laboratory trial measuring colour, acid value and peroxide value at two or three dosages will show the trade-off for your product.
Is this grade suitable for oils that are hydrogenated afterwards?
It is used for oils and fats that go on to hydrogenation or interesterification, where acid residues and soaps can affect catalyst life and product quality. Refiners should confirm compatibility with their own catalyst and process through trials before full-scale use.
What free acidity does the grade typically have?
Typical free acidity is at or below about 0.5 mg KOH/g, with a slurry pH typically in the range of 4.5–6.5. Guaranteed limits are stated on the Technical Data Sheet, and the measured value for each batch is reported on the Certificate of Analysis supplied with the shipment.