ABSTRACT
At the beginning of the 20th century, proteins were used to produce edible packaging and materials. Amino acids are classified on basis of the chemical groups that could interact as nonpolar amino acids, ionized polar amino acids, nonionized polar amino acids, and amino acids able to form –SS– bond. The polymerization of the amino acids occurs through the formation of an amide linkage between the carboxyl group of the given amino acid and the amino group of the next amino acid, with the resultant elimination of a molecule of water. The side chain of the amino acids can be either negatively or positively charged, polar, aliphatic, or aromatic. Most of the proteins found are heteropolymers, which consist of different types of amino acids with specific sequences and structures. The wet process/solvent process is a complete laboratory controlled process and rarely practiced on an industrial scale. Green composites with desirable properties can be derived by using fish proteins for different applications.
