this invention focuses on a novel process in which porphyridium cruentum biomass first undergoes a stage of cellular disruption and subsequently stages of recovery and purification in order to achieve the purified b - phycoerythin protein dye , using isoelectric precipitation and two - aqueous - phase systems . the steps of recovery and purification include isoelectric precipitation followed by a step of liquid / liquid extraction by means of two - aqueous - phase systems that use polyethylene glycol and phosphate salts . the bfe protein dye obtained in the two - aqueous - phase extraction step undergoes an ultrafiltration step in order to remove the polymer and to obtain a dye with a purity greater than 4 . 0 defined as the relationship between the absorbencies at 545 and 280 nm .