Oil fractionation is a physical process used to separate edible oils into fractions with different melting points based on their composition.
The Process Explained
Based on historical perspective in edible oil processing, the fractionation process is achieved through a series of controlled steps:
- Controlled Cooling: The process begins with the controlled cooling of the oil. This is not rapid cooling but a deliberate reduction in temperature over time, allowing for specific components to solidify.
- Partial Crystallization: As the oil cools, certain components, particularly those with higher melting points (typically saturated or longer-chain fatty acids), begin to solidify. This induces a partial, or 'fractional', crystallization within the bulk of the oil.
- Separation: Once crystallization has occurred, the mixture now consists of solid crystals suspended in the remaining liquid oil. The final step is to separate these two phases. The liquid portion is referred to as the olein, while the solid part is known as the stearin. This separation is commonly performed using methods such as:
- Filtration: Passing the mixture through a filter medium that retains the solid stearin crystals while allowing the liquid olein to pass through.
- Centrifugation: Using centrifugal force to separate the denser solid crystals from the lighter liquid phase.
This separation results in two distinct fractions:
- Olein: The liquid fraction, which remains fluid at lower temperatures.
- Stearin: The solid or semi-solid fraction, which has a higher melting point.
By repeating this process at different temperatures or using different cooling profiles, oils can be separated into multiple fractions, each with unique physical properties, making them suitable for various applications in the food industry and beyond.
