How Do You Process Soya Beans?

Soybeans are primarily processed through a multi-stage industrial method focused on extracting valuable oil and creating various by-products, including high-protein meal. This sophisticated process transforms raw beans into a range of commercial products crucial for food, animal feed, and diverse industrial applications.

The Core Stages of Soybean Processing

The industrial processing of soybeans typically involves a sequence of steps designed to efficiently separate the oil from the protein-rich meal, and then further refine these components for various uses.

1. Preparation and Dehulling

The initial phase is crucial for efficient oil extraction and involves preparing the raw soybeans.

• Cleaning: Raw soybeans are first cleaned to remove impurities such as dirt, stones, stems, and other foreign matter.
• Conditioning: The beans are then conditioned by adjusting their moisture content and temperature, which optimizes their structure for subsequent processing.
• Cracking: The conditioned soybeans are cracked into smaller pieces, typically two to eight cotyledons.
• Dehulling: This critical step involves separating the hull (outer skin) from the cotyledon (the inner part containing oil and protein). Dehulling is performed because hulls have little oil content and can absorb oil during the extraction process, making it less efficient. The hulls can be used in animal feed or as a biomass fuel.

2. Extraction

This is the stage where the oil is removed from the prepared soybean flakes.

• Flaking: Prior to extraction, the dehulled and cracked soybeans are often rolled into thin flakes. This increases the surface area, allowing for better solvent penetration and more efficient oil removal.
• Solvent Washing: The extraction process uses hexane or other suitable solvents to wash the soybean oil from these prepared soybean flakes. The solvent dissolves the oil, forming a mixture known as miscella. This method is highly efficient in extracting nearly all the oil present in the beans.

3. Desolventizing

After the oil extraction, the solvent must be removed from both the extracted oil and the remaining solid material (soybean meal).

• Meal Desolventizing: The solvent-laden soybean meal undergoes a process where it is heated to evaporate the hexane. The evaporated hexane is then recovered through condensation and reused in the extraction process, making the operation more economical and environmentally friendly. This heating also toasts the meal, which enhances its nutritional value and palatability for animal feed.
• Miscella Desolventizing: The miscella (the mixture of crude oil and solvent) also goes through a desolventizing step, usually through evaporation, to separate the crude soybean oil from the hexane.

4. Oil Refining and Processing

The crude soybean oil obtained after desolventizing undergoes further purification to make it suitable for various applications, especially for human consumption.

• Degumming: Phospholipids and gums are removed from the oil, which can cause cloudiness and reduce oil stability.
• Neutralization: Free fatty acids are removed, typically by reacting them with a caustic soda (alkali), which improves the oil's flavor and stability.
• Bleaching: The oil is treated with activated clays or carbons to remove pigments and impurities, resulting in a lighter color.
• Deodorization: Volatile compounds that cause undesirable odors and flavors are removed through steam distillation under vacuum, resulting in a bland, stable oil suitable for various food products like cooking oils, margarines, and salad dressings.

Valuable Soybean By-Products and Applications

Beyond crude and refined oil, soybean processing yields several important by-products with diverse industrial applications.

Soybean Meal

The solid material remaining after oil extraction and desolventizing is soybean meal, which is a highly valued protein source.

• It is primarily used as a key ingredient in animal feed for livestock, poultry, and aquaculture due to its exceptional protein content and balanced amino acid profile.
• Soybean meal can also be further processed into soy protein concentrates and isolates for human food products such as protein bars, meat alternatives, and nutritional supplements.

5. Biodiesel

Soybean oil is a significant feedstock for the production of biodiesel, a renewable alternative fuel.

• Biodiesel is produced through a chemical reaction called transesterification, where soybean oil reacts with an alcohol (like methanol) in the presence of a catalyst.
• This eco-friendly fuel offers a sustainable alternative to traditional petroleum diesel, contributing to reduced greenhouse gas emissions.

6. Oleochemicals

Soybean oil and its derivatives are also extensively used in the production of oleochemicals.

• These are chemicals derived from fats and oils, serving as sustainable and biodegradable alternatives to petrochemicals in a wide array of products.
• Applications include:
  • Soaps and detergents: Fatty acids from soybean oil are key components.
  • Cosmetics and personal care products: Used in lotions, creams, and emollients.
  • Lubricants: Environmentally friendly options for industrial and automotive uses.
  • Paints and coatings: As binders and film-formers.
  • Bioplastics and other industrial materials: Contributing to more sustainable manufacturing.

Summary of Soybean Processing Stages

For more detailed information on the diverse applications of refined soybean oil, you can explore resources on Soybean Oil Uses.