Textile Exchange

Soy pulp or Okara is used as the basic ingredient for soy yarn. Okara is a white or yellowish pulp consisting of the insoluble parts of the soybean which remain after filtering mashed soybeans for the production of soy milk. Okara is hence a by-product of soy milk and tofu manufacturing. It is primarily used as feed for cattle and pork but as well as food in different Asian countries.

Unfortunately there is limited visibility around involved processed, chemicals and their related environmental impact, in the transformation of Okara into fibres ready for spinning.

Soybean fibres are

• Made from the soybean cake
• The proteins are then distilled from the cake with the use of “auxiliary” agent and biological enzymes. The exact agents used in this process are not clear.
• The residues, once the proteins are extracted can be used as feed
• Proteins are then processed and modified; some “high polymers” are added. It is then cured before to be spun
• Acetate is then used to stabilize the fibre

Soybean Protein Fibre comes from China and processes described above are thought to be chemical intensive. There is however a lack of transparency about the exact nature of the chemistry used in this process.