Introduction: The Role of Vegetable Oil in Our Diet
Vegetable oil is a vital part of the human diet, providing:
- Fat-soluble vitamins (A, D, E, K)
- Essential fatty acids (omega-3 and omega-6)
- Enhanced taste, texture, and caloric value in food
Common sources include mustard, soybean, avocado, palm, sunflower, sesame, and cottonseed. The factory-level processing of these oilseeds involves:
- Pre-processing
- Extraction
- Refining
- Packaging and Storage
A food processing consultant helps design hygienic, cost-effective, and compliant vegetable oil processing lines.
Raw Material Handling and Pre-Processing
Raw Material Pre-checks
- Sorting and grading: Remove moldy or damaged seeds
- Cleaning: Remove stems, leaves, metal, and stones using vibrating screens, aspiration, and magnetic devices
- Drying: Reduce moisture from ~13% to 10% using multi-column dryers
Pre-processing Methods
- Dehulling: Removes outer layer to improve oil recovery
- Cracking and Flaking: Increases surface area for better solvent contact
- Conditioning: Uses steam heat to denature enzymes and enhance extraction
Extraction Methods
Mechanical Extraction
- Done via expeller presses, screw presses, or hydraulic presses
- Benefits: Low investment, cleaner oil
- Limitation: Lower yield compared to solvent extraction
Chemical Extraction (Solvent)
- Uses hexane, ethanol, methanol or other solvents
- Steps: Conditioning → Solvent contact → Miscella separation
- Yield: 90–98% oil recovery
- Needs solvent recovery systems and strict safety protocols
Solvent residue must be <5 ppm due to health risks like dizziness or long-term organ damage.
Oil Refining Process
Raw oil contains free fatty acids (FFA), phospholipids, pigments, and undesirable flavors. Refining improves:
- Stability
- Color and clarity
- Shelf life and taste
Key Steps in Refining:
Degumming
- Removes gums (phospholipids, carbohydrates, trace metals)
- Methods: Water degumming, acid degumming, enzymatic degumming
Neutralization
- FFA neutralized with caustic soda (NaOH)
- By-product (soap) can be separated and reused
Bleaching
- Uses activated earth, charcoal, or silica clay under vacuum
- Removes pigments and trace impurities
Deodorization
- High-temperature steam distillation
- Removes FFA, pesticides, off-flavors, and volatile contaminants
Winterization (Dewaxing)
- Removes waxes that cause cloudiness in cold
- Done by controlled chilling and filtration