Extraction of alginate from Sargassum muticum: process optimization and study of its functional activities

In the present study, alginate extraction from the brown seaweed Sargassum muticum was studied using single factor analysis. Response Surface Methodology-Central Composite Rotatary design (RSM-CCRD) was performed to reduce and optimize extraction temperature, alkali concentration, and consumption of solvent.

Different interaction effect of three extraction factors of temperature (60–100 °C), alkali (1–5 %), and aqueous ethanol (70–100 %) were studied to reduce residual waste. The result showed that the optimum extraction yield (13.57 %) was obtained with 86 °C temperature, 3 % alkali, and 93 % ethanol. A second order polynomial equation using multiple regression analysis was developed, and the predicted extraction yield showed a high coefficient of determination (R 2 = 0.98) with the experimental alginate yield.

The functionality of extracted alginate and residual supernatant left over after extraction were evaluated for total polyphenols and its antioxidant capacity. The extracted alginate was further characterized using fluorescence spectrophotometer and nuclear magnetic resonance spectroscopy. The 1H NMR data revealed that extracted alginate has an M/G ratio of 1.08 and η < 1.