Generally protein extraction most often uses different concentration salt solutions in water followed by centrifugation and/or filtration, although very small MW very hydrophilic proteins may be extracted in water alone. In some cases for the more larger MW, hydrophobic 'storage' proteins such as soy protein (7S and 11S), there may be ethanol or an acid or alkali (eg HCl, sodium hydroxide, ammonium hydroxide, etc) added in the water. The spray drying process usually used to turn the plant proteins into a usable food-ingredient powder will remove most water and even more ethanol from the final product.
The old 4-Type classification for extracting cereal proteins based on solubility was water-soluble were called albumins, salt-soluble called globulins, alcohol-soluble called prolamins, and acid or alkali-soluble called glutelins. In special cases, other solvents will be substituted for ethanol for example isopropanol or 2-chloroethanol.
Where stronger chemical solvents based on toxicity are used, such as hexane, is in defatting the flour before protein extraction for the vegetable oil recovery. very little of the hexane will dissolve in the aqueous phase, but there may be residual hexane in the extracted vegetable oil, but there are set limits as to how many ppm of residual hexane is allowed in the oils.
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Topic: Plant Protein Extraction - Do these methods use solvents? (Read 3940 times)