The way to keep couscous and semolina from clumping is to store both in an airtight, tightly sealed container, in a cool, dry cabinet. An open bag or a loosely closed jar draws in ambient moisture, and the grains stick together and harden.
Why does moisture cause clumping?
Semolina and couscous are finely milled wheat products with a large surface area, so they absorb moisture from the air quickly. Once moisture is absorbed, the starch swells, grains stick to each other, and uneven, hard lumps form that will not cook evenly. Jars kept near a stove or dishwasher clump faster for this reason.
Choose a screw-top glass jar or a container with a rubber gasket, and never leave the product in its original open bag. Close the container immediately after each use and avoid dipping a damp spoon into it.
How long do they stay fresh?
Kept dry and sealed, couscous and semolina hold their quality at room temperature for 6 to 8 months; refrigerated or frozen, that can stretch to up to a year. If you are storing a large amount, split it into smaller portions in separate containers so you are not opening and closing the main jar every time.
Whole-wheat semolina changes flavor sooner than white semolina because of the bran it contains; once opened, it is best used within 3 to 4 months.
Because couscous and semolina are milled finer than rice or bulgur, they absorb moisture faster; a jar of couscous sitting next to rice in the same cabinet can show clumping sooner than the rice does. That difference is the main reason two grains on the same shelf lose freshness at different speeds.
What kind of container works best?
The most practical choice for couscous and semolina is a wide-mouthed, screw-top glass jar; a wide opening makes scooping easier and lets you check the contents regularly. If you use a metal tin, one with a plastic liner keeps moisture from touching the metal directly.
A large bag of semolina or couscous can be divided into small, well-sealed freezer bags sized for one use and frozen; label each bag with a date. Measure out what you need with a dry spoon before the bag is opened and resealed.
Can clumped product still be used?
Lightly clumped couscous can be sieved or rubbed apart by hand and cooked as usual. But if the grains have turned grayish, smell musty, or show tiny insects, discard the batch — those signs mean moisture has been at work for a while. The same rule applies to similarly fine-milled bulgur and tarhana.