Alginate was recovered from Sargassum latifolium biomass using different conditions of alkali treatment.Box-Behnken experimental design was evaluated to study the influence of alkali:alga ratio, temperatureand time on alginate yield, and its molecular weight (MW) and mannuronic/guluronic acid ratio (M/G).The second-order polynomial equations were analyzed by appropriate statistical methods. Extractiontemperature and time were the most important factors during alginate alkaline extraction. MW andM/G ratio played an important role in controlling the reducing power of alginate. Increasing pH of thealginate solutions enhanced its reducing capacity, while thermal treatment showed a negative effect.Additionally, alginate exhibited good emulsion stabilizing capacities with diverse hydrophobic com-pounds. Emulsifying activity was less sensitive to temperature, ionic strength and more stable at acidicpH.