Quillaia is the milled inner bark or small stems and branches of the soapbark (Quillaja saponaria, Molina). Other names include Murillo bark extract, Panama bark extract, Quillaia extract, Quillay bark extract, and Soapbark extract. Quillaia contains high concentrations of saponins that can be increased further by processing. Highly purified saponins from quillaia are used as adjuvants to enhance the effectiveness of vaccines. Other compounds in the crude extract include tannins and other polyphenols, and calcium oxalate.

Quillaia is used in the manufacture of food additives, and it is listed as an ingredient in root beer and cream soda. The extract also is used as a humectant in baked goods, frozen dairy products, and puddings and as a foaming agent in soft drinks. It is used in agriculture for some "natural" spray adjuvant formulations.