Production of value added materials by subcritical water hydrolysis from krill residues extracted by supercritical carbon dioxide
The aim of this study was the determination of the best experimental conditions for the production of useful materials such as amino acids by subcritical water hydrolysis from supercritical carbon dioxide extracted krill residues and to compare the results with raw krill. Subcritical water hydrolysis efficiency from raw and de-oiled krill was examined over the temperature range of 200 to 280°C, ratio of material to water for hydrolysis was 1:50 g/ml and for water sample contact equilibration times of 5 min to decrease the decomposition of amino acids. Nitrogen and air were used as atmosphere at pressure estimated to be between 0.101 and 6.41 MPa. The hydrolysis efficiencies of glycine, arginine, and leucine were found to be increased with increasing water temperature, consistent with higher solubility at higher temperatures. The highest yield of amino acids in de-oiled krill hydrolysate was at 280°C. While, the highest amino acid yield in raw krill hydrolysate was at low temperature 200°C. Also, reducing sugar content was analyzed in both samples and the results showed that the yield of reducing sugar in deoiled krill hydrolysate was higher than that of raw krill hydrolysate.
Key words: Subcritical water hydrolysis, krill, amino acid, value added materials.