Black acid Soybean oil filtration process

         The filtration process to remove the black color and other impurities from acid-treated (or "acid soybean black") soybean oil to obtain pure oil involves several stages. Here's a general outline of the process, including the key steps:

 

1.Neutralization and Degumming (Optional, but Highly Recommended

Purpose: This step removes free fatty acids (FFAs) created by the acid treatment, as well as phospholipids (gums). These components can cause color issues and negatively impact the efficiency of later filtration steps.

Process: Neutralization: The acid-treated oil is mixed with a dilute alkaline solution (e.g., sodium hydroxide (NaOH), also known as caustic soda). This neutralizes the FFAs, converting them into soap.Degumming: Hot water is added to hydrate the phospholipids, causing them to become insoluble and precipitate.

2. Bleaching
Purpose: This is the core step to remove color pigments (including the black color) and other impurities responsible for discoloration.
Process:Addition of Bleaching Earth : The oil is mixed with a bleaching earth, typically activated clay (also called bentonite clay or Fuller's earth). The type and amount of bleaching earth used depend on the starting oil's quality and desired final color. The clay adsorbs color pigments, oxidized materials, and other impurities.Heating and Mixing: The oil-clay mixture is heated (typically under vacuum) to enhance adsorption efficiency. Thorough mixing is crucial to ensure good contact between the oil and the bleaching earth.
Powdered Activated carbon (Premsorb SIC grade) : Stage two, The oil is mixed with a PAC, The type and amount of PAC used depend on the starting oil's quality and desired final color. The PAC adsorbs color pigments, oxidized materials, smell and other impurities.Heating and Mixing: The oil-PAC mixture is heated to enhance adsorption efficiency for 30 minutes to 3 hours. Thorough mixing is crucial to ensure good contact between the oil and PAC Filtration to Remove Bleaching Earth ( Tonsil 230FF) and Premsorb PAC : The oil mixture is passed through a filter press or a similar filtration system to remove the spent material, which contains the adsorbed impurities. This filtration step is critical to remove the spent material; otherwise, it will re-contaminate the oil.Both the filtration must be done separately one removing tonsil and other removing Premsorb SIC.

 

3.Dewaxing (Optional, if required for specific applications):

Purpose: Dewaxing removes waxes, which can cause cloudiness or haziness in the oil, especially at lower temperatures.
Process:Chilling: The oil is cooled to a temperature where the waxes crystallize.
Filtration: The crystallized waxes are removed by filtration, typically using a plate and frame filter press or a continuous filter.

 

4.Polishing Filtration (Final Filtration):

Purpose: This is a final filtration step to remove any remaining fine particles, residual bleaching earth, or other impurities, ensuring the clarity and purity of the oil.
Process:Filter Media: Various filter media can be used, including:Plate and Frame Filters: Offer a high filtration area and efficiencyCartridge Filters: Good for removing small particles.Bag Filters: Suitable for pre-filtration.Membrane Filters: For very high purity applications.Filter Aids: Sometimes filter aids like diatomaceous earth (Radiolite 600) are used in the polishing filtration step to improve filtration efficiency and clarity, although with acid-treated oil, it would be essential to ensure it doesn't reintroduce color or other undesirable components.

 

5.Deodorization (Optional, but Usually Included):

Purpose: Deodorization removes volatile compounds responsible for undesirable odors and flavors. This step is common to produce edible oils with a neutral taste and smell.
Process:Steam Stripping: The oil is heated under vacuum and steam is passed through it. The steam strips away volatile compounds.Cooling: The deodorized oil is cooled and can be further processed for packaging.