How is Soy Oil Extracted?

Soy oil is extracted from soybeans through a multi-step process that primarily involves mechanical preparation followed by solvent extraction.

The extraction of soy oil is a common industrial process designed to efficiently separate the oil from the soybean meal. This typically involves physically preparing the beans and then using a chemical solvent to dissolve and remove the oil.

The Step-by-Step Process

The process of extracting oil from soybeans involves several key stages to prepare the beans and isolate the oil.

Here are the general steps involved, as outlined in the reference:

1. Soybean Preparation:
   • The whole soybeans are first cracked to break them into smaller pieces.
   • Their moisture content is adjusted to optimal levels for subsequent processing.
2. Heating:
   • The cracked and conditioned beans are then heated to a specific temperature range, typically between 60 and 88 °C (140 and 190 °F). This heating step helps to rupture the oil cells and prepare the oil for extraction.
3. Flaking:
   • After heating, the beans are rolled into thin flakes. This increases the surface area of the soybean material, making the oil more accessible for extraction.
4. Solvent Extraction:
   • The most critical step for high oil yield is solvent-extracted with hexanes. The soybean flakes are mixed with a solvent, commonly hexane, which dissolves the oil. The oil-solvent mixture (miscella) is then separated from the solid meal.
5. Solvent Removal & Refining:
   • The solvent is evaporated from the miscella, leaving behind the crude soybean oil. The solvent is typically recovered and reused.
   • The crude oil is then refined through various processes (like degumming, neutralizing, bleaching, and deodorizing) to remove impurities and unwanted compounds, resulting in edible soybean oil.
   • The refined oil can then be blended for different applications and is sometimes hydrogenated to alter its physical properties for specific uses.

Why Solvent Extraction?

While mechanical pressing can extract some oil, solvent extraction, particularly with hexanes, is widely used in the industry because it is highly efficient. This method allows for the recovery of over 95% of the oil contained within the soybeans, making it economically viable for large-scale production. Hexane is effective because it readily dissolves the oil and can be easily separated from the oil and the solid meal afterwards.

Key Stages Summarized

For further details on the properties of soybean oil or its various applications, you might explore resources on vegetable oils or industrial oil processing.