The invention comprises a method of industrial extraction of alginates from brown seaweeds of the family Sargassaceae of the order Fucales, as well as the product resulting from the method. The method includes the following stages: preparation of raw materials, crushing of the algae, pressure boiling of the algae, mixing the boiled algae with water, purification of the diluted algal mass, extraction of alginic acid, washing of the alginic acid, dehydration of the alginic acid, treatment of the alginic acid with sodium hydrogen carbonate, clarification of resultant sodium alginate solution, precipitation of sodium alginate gel, and drying of the sodium alginate gel.