Ion-exchange membrane mediated electrodialysis of scallop broth: Ion, free amino acid and heavy metal profiles

Ion-exchange membrane mediated electrodialysis desalination of scallop broth was performed and efficacy to produce low salt scallop broth, minimum percolation of free amino acids and reduction of heavy metals levels (Cd, As, Pb, Cu, Fe and Zn) in the scallop broth assessed. The influence of electrodialysis on changes in ion and free amino acids in diluted scallop broth was determined for various pH conditions (6.4, 4.5, 3.5 and 2.5). Free amino acids were not leached remarkably after electrodialysis. Taurine, glycine and arginine combined constituted 86.6%, 83.9%, 84.9% and 81.1% of the total free amino acids by weight upon electrodialysis treatment at pH conditions 6.4. 4.53 3.5 and 2.5. respectively. A remarkable decrease of salt content was noted. The mean concentration of Na+ and Cl- ions dropped to 1.1% and 3.7% of the pretreated concentration. Ion-exchange membrane mediated electrodialysis desalination of scallop broth was feasible with reduced amino acid percolation. The concentration of the predominant metallic constituents (Zn, Mg, Fe and Cu) declined in a pH dependent manner except for Mg. Marginal changes occurred in the concentrations of Cd, Pb, Ni and Cr. (c) 2006 Elsevier Ltd. All rights reserved.