© Denzil Green
Tapioca is a starch.
It comes from a tropical plant root called "cassava", which grows in Africa and South America. The starchy root is roasted, and ground.
Tapioca has little taste on its own, and is used instead for its thickening abilities. Use where you want a high gloss, such as in fruit pies.
Tapioca can be purchased in pearl ("bead"), instant (also called "granulated" or "quick-cooking") and in starch (or flour) form.
In a liquid, Tapioca reaches its maximum thickening power at 185 F (85 C.)
Literature & Lore
Previously Java was our principal source of supply of tapioca starch taken from the root of the cassava. The new dessert is made from a sorghum starch but produces a pudding almost identical to the prewar kind. This new tapioca turns out thick and creamy, really delicious, and can be used in numerous pudding variations and as a thickening agent for pies. But don't try using it to thicken a souffle, or as a binder for meat loaf. Sorghum starch has certain differences from the starch of cassava and these differences must be considered in its cooking treatment. The home economists of the General Foods Corporation have worked out new recipes using the dessert, to replace the classic favorites which starred Minute Tapioca. A recipe folder accompanies each box and for happy results observe the rules to the letter."
-- Paddleford, Clementine (1898 - 1967). Food Flashes Column. Gourmet Magazine. October 1945.