Extraction Optimization for Phlorotannin Recovery from the Edible Brown Seaweed Ecklonia Cava

Phlorotannins, marine polyphenols from the brown seaweeds, are a promising biologically active substance. This study aimed to optimize the extraction conditions for phlorotannin recovery from the brown seaweed Ecklonia cava using response surface methodology. Ethanol concentration (X₁, %), extraction temperature (X₂, °C), and extraction time (X₃, h) were chosen as independent variables. The dependent variables were total phlorotannin content (TPhC; Y₁) and yield of phlorotannins (Y₂). Estimated optimal conditions were as follows: TPhC (Y₁): X₁ = 95%, X₂ = 80°C, X₃ = 22.8 h, and yield of phlorotannins (Y₂): X₁ = 88.3%, X₂ = 80°C, X₃ = 24 h. Predicted values of dependent variables under each optimal condition were TPhC (Y₁) = 570.2 mg phloroglucinol equivalents/g (mg PGE/g, dry basis) and yield of phlorotannins (Y₂) = 7.8% and were similar to the experimental values. In addition, content of dieckol, which is known as an indicator of phlorotannin products, was measured. Dieckol contents of the phlorotannin extracts with the highest (565.7 mg PGE/g) and lowest (315.4 mg PGE/g) TPhC were 49.1 and 34.4 mg/g (dry basis), respectively.