Accumulation of phlorotannins in the abalone Haliotis discus hannai after feeding the brown seaweed Ecklonia cava

Value-added abalone Haliotis discus hannai containing bioactive phlorotannins is produced by simply changing the feed to phlorotannin-rich brown seaweed Ecklonia cava 2 weeks prior to harvesting. We assessed the accumulation of phlorotannins by feeding with the seaweed after 4 days of starvation. Reverse-phase high-performance liquid chromatography afforded isolation of the major phlorotannins, which were identified by mass spectrometry and ¹H-nuclear magnetic resonance to be 7-phloroeckol and eckol. Throughout the E. cava feeding period of 20 days, 7-phloroeckolol accumulated in the flesh (foot muscle tissue), up to 0.85?±?0.21 mg g^?1 dry weight of tissue after 12 days. Eckol reached 0.31?±?0.08 mg g^?1 dry tissue after 14 days. Feeding Laminaria japonica as a control, we detected no phlorotannins in the abalone muscle tissue. Abalone seaweed consumption and growth rate were similar when fed with E. cava or L. japonica for 20 days. Reduction in phlorotannins to half-maximal accumulation took 1.0 and 2.7 days for 7-phloroeckol and eckol, respectively, after replacement of the feed with L. japonica.