Soy bean field
Soy bean field

Soy proteins are one of the most important vegetable proteins in the world market.

The soya beans are composed of:

  • Protein: ~40% (of which about 80% is water soluble).
  • Oil: ~20%
  • Fibers: ~10%
  • Carbohydrates and salts: ~20%
  • Water: ~10%





Complete process lines for Soy Protein Isolate (SPI) and by-products
GEA Process Engineering supply complete process lines for Soy Protein Isolate (SPI) and the valuable by-products from the process such as fibers/insoluble proteins, carbohydrates and salts.

Liquid treatment and refining
The feed material for production of SPI is defatted soy flakes. Water is used for the soaking of the soy flakes and the extraction of the water soluble soy protein. Acid is used to precipitate the protein solution at the iso-electric point. The protein curd is then separated and washed with water in decanters and re-solubilized by neutralization. The protein content in the product is now 90% or more (based on solids). The by-product from the extraction contains fibers and the remaining un-dissolved proteins. Depending on the final use of the SPI - be it in fortified energy drinks, as meat replacer or in powdered infant formula/baby food - the protein solution can be pasteurized or UHT treated before further processing.

Spray drying of Soy Protein Isolate (SPI)
Soy Protein Isolate (SPI) is spray dried in a GEA Niro NOZZLE TOWER™ using atomization by high pressure nozzles and a high drying air temperature. The high protein content in the concentrate makes it very viscous. Low total solids content is then necessary in the feed and the resulting powder will consist of fine particles. To avoid powder loss, the process air is passed through bag filters. By selecting a Fluidized Spray Dryer FSD™ , it will be possible to produce an agglomerated free-flowing powder.

Processing of the by-products
The water used for soaking and extracting the soy flakes contains carbohydrates and salts. The water is removed by evaporation and after condensation polished in a reverse osmosis plant. The water can now be used for cleaning purposes or returned to the extraction process thereby saving water.

The concentrate with the carbohydrates and salts are mixed with the fiber/un-dissolved protein fraction from the extraction. This mixture is then dried in a Ring Dryer and used for animal feed.

Powder handling and packaging
Both SPI and by-products can be conveyed to silos and bagged off in suitable bags.