Quillaia is the milled inner bark or small stems and branches of the soapbark (Quillaja saponaria).
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.
[1] The extract also is used as a humectant in baked goods, frozen dairy products, and puddings and as a foaming agent in soft drinks.
[3] Novavax uses a highly purified quillaja extract as an adjuvant in its veterinary and human vaccines.