Sequential extraction process and physicochemical characterization of R-phycoerythrin and agar from red macroalgae Gracilaria birdiae

Abstract

This study evaluated the sequential extraction of R-phycoerythrin (R-PE) and agar from the red macroalgae Gracilaria birdiae and the effects on yield, recovery, purity index and physicochemical characterization of both biomolecules. Three R-PE extraction and partial purification strategies were evaluated and the three most promising pigmented fractions were F25/35, F35/45 and F25/45 with purity/yield indexes 1.64/0.17, 0.71/0.44 and 0.56/ 1.20 mg.g−1 dw, respectively. In addition to the purity index, yield and recovery, optimizations 1 and 2 resulted in obtaining pigments with high intensity of red color, confirmed by the values of parameter a*: 78.30 ± 0.01, 64.07 ± 0.03 and 60.96 ± 0.02, for fractions 25/35, 35/45 and 25/45, in that order. The agar obtained from the residue of the extraction of R-PE (ARES-Gb) showed a yield of 31.64 %, higher than those reported in the literature when extracted from integral wet or dry macroalgae. In addition, RES-Gb had physicochemical and rheological properties similar to commercial agar. Therefore, the development of the biotechnological process proposed contributes to the maximum use of G. birdiae, to the valorization of this renewable source and to the blue economy.