Soybean processing primarily involves extracting oil from the beans, which also yields a high-protein meal. The conventional method is a multi-step chemical extraction process.
According to the reference, the conventional soybean extraction process consists of four steps; preparation, extraction, solvent recovery from miscella and desolventizing/toasting of meal. Modern processing facilities are often large-scale operations encompassing numerous operations.
Here's a breakdown of the conventional process steps:
Steps in Conventional Soybean Processing
The conventional method relies on using a solvent, typically hexane, to separate the oil from the solid meal.
- Preparation
- This initial phase gets the soybeans ready for efficient oil extraction. It usually involves cleaning the beans to remove foreign materials, cracking them into smaller pieces, dehulling (removing the outer hull), and conditioning or flaking the cracked beans. Flaking increases the surface area, making the oil more accessible to the solvent.
- Extraction
- In this crucial step, a solvent (like hexane) is used to dissolve the oil from the prepared soybean flakes. The solvent is mixed with the flakes, pulling the oil into the liquid phase. This results in two main products:
- Miscella: A mixture of solvent and soybean oil.
- Defatted Meal: The solid soybean flakes from which most of the oil has been removed.
- In this crucial step, a solvent (like hexane) is used to dissolve the oil from the prepared soybean flakes. The solvent is mixed with the flakes, pulling the oil into the liquid phase. This results in two main products:
- Solvent Recovery from Miscella
- The miscella (solvent + oil) needs to be separated to obtain the pure soybean oil and recover the solvent for reuse. This is typically done by heating the miscella, which causes the lower-boiling-point solvent to vaporize. The vaporized solvent is then condensed and recycled back into the extraction process.
- Desolventizing/Toasting of Meal
- The defatted meal still contains residual solvent. This step removes the remaining solvent from the meal, often using heat and steam. This process is called desolventizing. Simultaneously, the meal is often toasted with steam, which not only further removes solvent but also helps to deactivate anti-nutritional factors present in raw soybeans and improves the meal's nutritional value and palatability, especially for animal feed.
Modern soybean processing plants integrate these steps into large, continuous operations designed for high efficiency and volume. Many additional operations, such as refining the crude soybean oil (degumming, neutralizing, bleaching, deodorizing) to make it edible, are also part of the overall process in a modern facility.
