Cell pretreatment with ethylenediaminetetraacetic acid for selective extraction of C-phycocyanin with food grade purity.

C-phycocyanin (C-PC) is a natural blue dye, and depending on its purity, which is measured by the ratio between the absorbance of the chromophore (A620 ) and the absorbance of the proteins (A280 ), it can be used in food (purity > 0.7), cosmetics (purity > 1.5), and therapeutic treatments (purity > 4.0). Several physical, chemical, and enzymatic methods of extraction are reported, however, few are able to extract C-PC with purity above 0.7. An innovative method of C-PC extraction with food grade purity from wet Spirulina platensis biomass is proposed. The cells were pretreated with ethylenediaminetetraacetic acid and subsequent C-PC extraction was performed with tris-(hydroxymethyl) aminomethane-SO4 buffer. C-PC was released after 12 h of cell pretreatment. Six variables of the extraction process were evaluated. The extraction temperature significantly influenced C-PC extraction yield and purity. In the best condition of cell pretreatment and extraction, C-PC with purity of 1.0 and extraction yield of 129.0 mg/g could be obtained to be used as a food dye without any purification process. Lastly, an ultrafiltration process was integrated and C-PC was concentrated 8.8-fold, resulting in purity of 1.6 and recovery of 93.4%.