Concentration of aqueous residue from isada krill using freezing-thawing technique

Abstract

The concentrated aqueous residues from the recovery process of useful oil-soluble components from Isada krill were examined by freezing-thawing technique. The aqueous residue was completely frozen into spheres or cuboids of different sizes at －20℃ or －80℃, and then thawed at room temperature (26 ± 2℃). The concentration index was defined as the ratio of the Brix concentration of the melted solution to that of the original solution. The changes in the cumulative fraction and concentration index of melted solution during the thawing process were measured. The freezing temperature had no significant effect on the thawing process. For all the frozen samples, the relationship between the cumulative fraction and concentration index of the melted solution was roughly represented by a single straight line, and the concentration index of the solution obtained by thawing half of the frozen sample was about 1.4. It was shown that the original solution could be concentrated twice when the freezing-thawing operation was repeated twice. However, further repeated operation had no effect on concentration.