EXTRACTION OF AMINO-ACIDS FROM PROTEIN HYDROLYSATES BY ELECTRODIALYSIS

Protein hydrolysates were obtained by acid hydrolysis from animal or h uman residues, such as poultry feathers, ox blood and human hair. Afte r neutralization and discolouration with active charcoal, the hydrolys ates were treated by successive electrodialysis (ED) in order to extra ct amino acids into several fractions. The current density and pH were optimized for each ED operation performed with preindustrial pilot sc ale equipment. The first step was the demineralization of amino acid m ixtures using an ED stack with two compartments. The salt removal was achieved with extraction degrees higher than 90% and current efficienc ies of about 80%. In the most favourable case, the amino acid losses d id not exceed 10%. The second step was the extraction of the charged a mino acids using an ED stack with four compartments. Three fractions w ere obtained, corresponding to the acidic, basic and neutral amino aci ds. The extraction degrees varied from 80% to 100%. In the third step, the fractionation of basic amino acids on the one hand, and neutral a mino acids on the other hand, was carried out with enrichment degrees varying from 50% to 80%. (C) 1998 SCI.