The present invention is directed to a method of modifying feather raw material comprising the steps of: (a) treating feather raw material in a first aqueous solution containing sulphite ions, wherein the treatment is carried out at pH 6 –8, reaching temperature of about 90 degrees Celsius, the treatment lasting at least 30minutes； (b) separating the sulfonated feather material obtained from step (a)；(c) treating the sulfonated feather material in a second aqueous solution, wherein the treatment is carried out at pH 1.5 –3.0 and at temperature of 10 –30 degrees Celsius, the treatment lasting at least 5 minutes；and (d) adjusting the pH of the second aqueous solution or the feather material obtained from the second aqueous solution to at least pH4.5 –5.5.The produced protein-rich modified feather product is suitable as an additive for use, e.g., infood industry, animal feeds and cosmetics.
