Ammonium alginate is the ammonium salt of alginic acid, a seaweed-derived polysaccharide that emulsifies, thickens, and stabilizes foods. Like other alginates it forms viscous solutions and, in the presence of calcium, firm gels, properties exploited in restructured foods, dessert gels, bakery fillings, and the membranes of popping boba. The ammonium form offers specific solubility and gel characteristics that suit certain formulations better than the more common sodium or calcium salts. As a soluble fiber it passes through the gut largely unabsorbed, and regulators permit its use with established safety evaluations. Its seaweed origin appeals to formulators seeking plant-based, label-friendly hydrocolloids, and it performs reliably across the mildly acidic to neutral pH range of most foods.