Subcritical water extraction for recovery of phenolics and fucoidan from New Zealand Wakame (Undaria pinnatifida) seaweed

In this study, subcritical water extraction (SWE) was investigated for the recovery of phenolics, phlorotannins, and fucoidan from New Zealand Wakame. Maximum total phenolics and phlorotannin content of 29.9 mg +/- 1.8 mg gallic acid equivalent/g dry weight seaweed (mg GAE/g dw) and 0.99 mg +/- 0.004 mg phloroglucinol equivalents (PGE)/g dw respectively were achieved at 210 ?C, at a solid content of 10 g/L, and at 15-20 min. Maximum fucoidan yield of 46 mg/g dw was obtained at 120 ?C, 5 min, and 20 g/L. In comparison, conventional hot water extraction (HWE) achieved lower phenolic and phlorotannin content at 1.27 mg +/- 0.01 mg GAE/g dw and 0.69 mg +/- 0.1 mg PGE/g dw respectively. Also, fucoidan was not detected by HWE and antioxidant activity was much lower compared to SWE. These results indicate the effectiveness of SWE as an alternative to conventional extraction methods.