Regenerated protein fibers were produced from cereal grains such as soy and peanuts in the 1950s. Regenerated fibers from peanut under the trade name Ardil and proteins from corn zein marketed as Vicara and even from soybean were produced on a commercial scale and used for industrial applications [09Poo]. Some of the properties of the fibers regenerated from plant and other protein sources are shown in Table 54.1. As seen from the table, protein fibers regenerated from cereal proteins have considerably lower strength than the weakest protein fiber, wool. More importantly, the regenerated protein fibers have substantially lower wet strength which makes them unusable for practical applications. Various approaches have been used to improve the properties of the regenerated fibers.