Continuous microwave-assisted step-by-step extraction of bioactive water-soluble materials and fucoidan from brown seaweed Undaria pinnatifida waste

Continuous extraction production process by microwave-assisted extraction (MAE) using brown macroalgae Undaria pinnatifida waste was investigated to obtain proteins and a sulfated polysaccharide, fucoidan, at low (55-160 degrees C) and high (150-170 degrees C) temperatures. At the lower temperatures, protein extraction increased with increasing extraction condition severity. All extracted proteins exhibited angiotensin-converting enzyme inhibitory activity. The proteins extracted at 100 and 120 degrees C for 20 and 5 min, respectively, displayed the highest activities (evaluated as IC50 of protein concentration), which were 0.03 and 0.05 g/L, respectively. Subsequently, the highest fucoidan yields were attained after extraction at 150 degrees C for 30 min (12.3% based on the raw material) during the higher temperature extraction process. The yield was equivalent to that extracted directly by the MAE treatment (without treatment at a lower temperature). The results indicated that the continuous extraction of protein and fucoidan using MAE is possible. Moreover, U. pinnatifida waste could potentially be used as feedstock to provide valuable chemicals.