In order to extract phospholipids from soybeans, we can discuss the following aspects:
I. Raw Material Pretreatment
(1) Raw Material Selection and Inspection
The primary raw material for phospholipid production is soybean oil. When selecting soybean oil, it is essential to ensure its source is reliable and its quality meets the required standards. Typically, lightly refined crude oil is preferred because it contains relatively higher phospholipid content. During raw material inspection, parameters such as acid value, color, and moisture content of the soybean oil must be tested. For example, an excessively high acid value may indicate that the oil has undergone some degree of oxidation or hydrolysis, which can affect phospholipid quality and extraction efficiency. Similarly, overly dark color may suggest the presence of excessive impurities, while high moisture content could lead to hydrolysis issues during subsequent processing. Soybean crude oil can be obtained by screw press, we can provide different capacity screw oil press.
(2) Filtration and Impurity Removal
Soybean oil often contains impurities such as sediment and meal particles, which can negatively impact phospholipid extraction and quality. These impurities must be removed through filtration. Plate-and-frame filters or bag filters can be used for this purpose. The filtration medium in plate-and-frame filters may consist of filter paper or fabric, offering the advantage of high precision to effectively remove fine particulate impurities. Bag filters, on the other hand, feature a large filtration area and ease of operation. The filtered soybean oil is more purified, providing a solid foundation for subsequent phospholipid extraction.
II. Hydration Degumming
(1) Hydration Principle
Hydration degumming leverages the hydrophilic nature of phospholipids. By adding an appropriate amount of water to the oil, phospholipids absorb water, swell, and aggregate into gum particles, which are then separated from the oil. Phospholipid molecules contain hydrophilic groups such as phosphate and choline. When water is added, these groups interact with water molecules, causing phospholipid molecules to aggregate. During this process, phospholipids transition from the oil phase to the aqueous phase, achieving separation from the oil.
(2) Hydration Operation
- Water Addition Control: The amount of water added is generally 1.5–3 times the phospholipid content in the oil. Insufficient water will prevent complete hydration, leading to incomplete degumming, while excessive water may result in overly fine gum particles that are difficult to separate. Additionally, too much water may carry other impurities into the gum particles. For example, for soybean oil with a phospholipid content of 2%–3%, 3–6 kg of water can be added per 100 kg of oil.
- Temperature Control: The hydration temperature is typically maintained at 70–90°C. Within this range, phospholipid hydration occurs rapidly, and the oil's viscosity is reduced, facilitating gum particle aggregation and separation. Excessively high temperatures may cause phospholipid oxidation, while temperatures that are too low will slow the hydration reaction.
- Stirring Speed: Stirring ensures thorough mixing of water and oil, promoting phospholipid hydration. The stirring speed is usually controlled at 60–100 rpm for 30–60 minutes to ensure complete hydration. After hydration, the mixture is allowed to settle for 4–8 hours to allow gum particles to precipitate to the bottom. The upper oil layer and lower phospholipid gum layer are then separated via decantation.
III. Separation and Drying
(1) Separation Methods
- Centrifugal Separation: This is a commonly used method for rapidly and effectively separating phospholipid gum from oil. High-speed rotation of the centrifuge (typically 3,000–5,000 rpm) generates centrifugal force, causing the gum particles and oil to separate into distinct layers. This method offers high efficiency and yields relatively pure phospholipid gum.
- Filtration Separation: Alternatively, filtration separation can be employed using vacuum or pressure filtration equipment to isolate the phospholipid gum. During filtration, pressure must be carefully controlled to avoid damaging the gum structure. Suitable filter paper or fabric can be selected as the filtration medium to ensure effective retention of the gum.
(2) Drying Treatment
The separated phospholipid gum contains significant moisture and requires drying. Methods such as vacuum drying or spray drying may be used.
- Vacuum Drying: The phospholipid gum is dried at a relatively low temperature (usually 60–80°C) under vacuum conditions. The vacuum environment lowers the boiling point of water, enabling evaporation at reduced temperatures and preventing phospholipid oxidation or denaturation. Drying typically takes 4–8 hours until the moisture content meets the required standard (generally below 1%–3%).
- Spray Drying: The phospholipid gum is emulsified and sprayed into a drying chamber. Hot air at 180–220°C causes instantaneous evaporation of moisture, yielding dried phospholipid powder. This method offers rapid drying and produces a powdered product that is easy to store and transport.
IV. Refining and Purification
(1) Decolorization
The extracted phospholipid may exhibit some coloration due to pigments in the raw material or generated during processing. Decolorization can be achieved using adsorbents such as activated carbon or clay. The phospholipid is mixed with the adsorbent under controlled temperature (usually 60–80°C) and stirring conditions for 30–60 minutes. The adsorbent captures the pigments, which are then separated via filtration.
we can use oil refinery machine to do the decolorization and deodorization.
(2) Deodorization
Phospholipids may develop undesirable odors during processing, necessitating deodorization. Vacuum steam deodorization can be employed, where the phospholipid is heated to 120–150°C under vacuum, and steam is introduced to carry away odorous compounds. The process typically lasts 1–3 hours, depending on the intensity of odors and product requirements.
(3) Ultrafiltration Purification
Ultrafiltration, a membrane separation technology, effectively removes impurities and small molecules from phospholipids. By selecting an appropriate membrane pore size, the phospholipid solution is passed through the ultrafiltration membrane, which retains impurities while allowing phospholipid molecules to pass through. Operational pressure is maintained at 0.1–0.3 MPa, and flow rates are adjusted based on equipment specifications and solution volume.
V. Concentration and Packaging
(1) Concentration
For high-concentration phospholipid products, thin-film evaporation can be used for concentration. In the evaporator, the phospholipid solution forms a thin film under heating, and water and volatile compounds are rapidly evaporated under low pressure (typically 1–5 kPa), increasing phospholipid concentration. The final concentration can be adjusted to market demands, such as raising phospholipid content to over 90%.
(2) Packaging and Storage
Packaging material selection is critical for phospholipid preservation. Aluminum foil bags or plastic drums are commonly used. For powdered phospholipids, aluminum foil bags effectively prevent moisture absorption and oxidation. For liquid phospholipids, airtight plastic drums prevent leakage and spoilage. During storage, phospholipids should be kept in a cool, dry, and well-ventilated area away from direct sunlight and high temperatures, as these conditions can accelerate oxidation and degrade quality. Typically, phospholipids have a shelf life of 1–2 years, depending on product quality and storage conditions.
Through the above production process, high-quality phospholipid products can be manufactured to meet the demands of various industries, including food, pharmaceuticals, and cosmetics. Strict control of process parameters at each stage is essential to ensure consistent and safe product quality.
