Simplified Two-Stage Method for the Recovery of B-Phycoerythrin from Porphyridium Cruentum and Evaluation as a Natural Food Grade Colourant
摘要
Phycoerythrin (B-PE) is one of the most characteristic phycobiliproteins; its commercial use depends on its degree of purity. In this work, a simple methodology based on tangential flow ultrafiltration has been developed for the extraction, concentration, and partial purification of B-PE from Porphyridium cruentum. It was possible to extract up to 84% of the B-PE contained in the biomass using buffer phosphate (0.1 M pH 5.5) as a solvent. However, the purity ratio remained lower than 0.29. Ultrafiltration membranes of molecular weights of 10, 50, and 100 KDa (MWCO) were tested for concentration and purification purposes. The best results were obtained with the smallest pore size (10 KDa), achieving a purity ratio of 0.70, 84% recovery, a global yield of 71%, and a final concentration of 0.21 mg·mL−1 (14-fold concentration). The specific permeate rate and resistance to filtration under these conditions were also analysed. The overall process resulted in a B-PE recovery yield of 71%. Two preservatives were evaluated to improve the stability of the obtained aqueous solution. Their performance was evaluated at different temperatures and radiation exposure conditions. The stability of the B-PE solution, determined as the lifespan at 25 °C, was increased from the initial value of 40 days to 75 and 133 days by the addition of glucose and carrageenan, respectively. In the same way, the stability of the protein increased with the use of these two additives in additional experiments at 4 and 42 °C. Overall, these results demonstrate that the use of a two-step system consisting of initial clarification followed by ultrafiltration constitutes a simple and scalable method to obtain B-PE colouring extracts with food-grade purity.