Response surface optimization of enzyme-assisted extraction of R-phycoerythrin from dry Pyropia yezoensis

The effect of polysaccharidases (agarase and cellulase) on R-phycoerythrin (R-PE) extraction from dry Pyropia yezoensis was investigated and optimized. First, single-factor experiments of agarase dosage, cellulase dosage, temperature, hydrolysis time, and solid/liquid ratio were performed and factors for further optimization were selected based on Pearson's correlation analysis. Next, response surface methodology (RSM) based on a three-level three-factor Box Behnken Design (BBD) was applied to optimize R-PE extraction conditions including agarase dosage, temperature, and solid/liquid ratio. The experimental data were adequately fitted into the second-order polynomial models. Under the optimized extraction conditions, agarase dosage (104 U g(-1) biomass), cellulase dosage (100 U g(-1) biomass), temperature (29 degrees C), hydrolysis time (5 h), and solid/liquid ratio (1/26 w/v), the experimental yield of R-PE was 3.33 times greater than the extraction method lacking enzyme treatment, and 1.85 and 2.82 times, respectively, greater than the yields obtained by freeze-thaw and maceration experiments. The optimized enzyme-assisted extraction method enhanced the purity index 1.95-fold. R-PE extraction from dry P. yezoensis using agarase and cellulase is a promising method to utilize some high-value compounds from P. yezoensis.