Abstract: On the basis of one-factor-at-a-time experiments, an L16(43) orthogonal array design was performed to optimize process conditions for aqueous two-phase extraction of R-phycoerythrin from Porphyra yezoensi. The effects of PEGs of different molecular weights, PEG 4000 dosage, the concentration of Na2SO4 as the phase-forming salt and ionic strength on the extraction of R-phycoerythrin were examined. The results indicated that the optimal aqueous two-phase extraction conditions were PEG 4000 as the phase-forming polymer at 6%, Na2SO4 concentration 13%, NaCl concentration 1.5%. After the optimized aqueous two-phase extraction, the purity of R-phycoerythrin was increased to 0.727 from 0.187, showing a 2.25-fold increase. Therefore, aqueous two-phase extraction is more suitable for R-phycoerythrin extraction than ammonium sulfate precipitation.

Key words: Porphyra yezoensis, R-phycoerythrin, aqueous two-phase extraction, optimization