On Food and Cooking

absorb moisture and flavor, thicken
puddings and pie fillings, and nowadays to
provide chewy “bubbles” in teas and other
drinks, are translucent, glossy, and elastic,
and based on the same principle as the
starch noodle. They are spheres 1–6 mm
across made up of tapioca starch granules
held together by a matrix of gelatinized
tapioca starch (about 17% amylose). A wet
mass of the starch granules (40–50% water
by weight) is broken up into coarse grains,
and the grains then fed into rotating pans,
where they roll around and gradually
agglomerate into little balls. They’re then
steamed until a little more than half the
starch is gelated, mostly in the outer layer,
and then are dried, so that a firm
retrograded starch matrix forms. When
cooked in liquid, they soak up water and
the rest of their starch gelates while the
retrograded matrix maintains their
structure.