Recovery of North Pacific krill Euphausia pacifica proteins via isoelectric solubilization/precipitation using food additives

Abstract

 North Pacific krill Euphausia pacifica has very low market value due to its small size and quick quality degradation. To add high value to the krill, the effect of isoelectric solubilization/precipitation using food additives to recover the krill protein was investigated. The krill protein could be solubilized by adding alkaline additives (K₂CO₃, Na₂CO₃, K₃PO₄ or Na₃PO₄) and precipitated by adding organic acids (citric acid, dl-malic acid, l-tartaric acid or acetic acid). The protein recovery yield was the highest when solubilized at 10.0 and precipitated at pH 4.0. In particular, the treatment using K₂CO₃ and citric acid showed the highest protein recovery yield (58.8%) which was higher than that of the control (NaOH and HCl treatment; 40.9%). SDS-PAGE pattern, proximate composition, mineral composition and amino acid composition of the protein recovered by K₂CO₃ and citric acid treatment were comparable to those of the control. From the above, it can be concluded that the isoelectric solubilization/precipitation using K₂CO₃ and citric acid is effective to recover proteins from the krill.