Curing and Drying Soybeans for Storage Without Mold

Why the crop is finished under cover

The plants come out of the bed a few days before they are fully dry, because leaving them standing to that point means the pods split and throw the beans away. What that leaves you with is a harvest that is nearly, but not quite, ready to store. Curing is the stage that closes that gap, and it happens somewhere the pods can dry hard, and can split if they want to, without losing a single bean.

You need a covered, airy, shaded space: a shed with the door propped open, a carport, a greenhouse with the vents open, a spare room with a window ajar. It must be dry and moving with air, and must not be sealed, sunlit or damp. Direct sun splits the seed coats, a sealed space traps the moisture coming out of the plants, and a damp shed grows mold on the whole batch.

Two to three weeks is typical, though a warm, airy space can do it in ten days and a cool damp autumn can take a month. There is no penalty for taking longer, so long as the air keeps moving.

Hang or spread the plants the same day you cut them. A pile of stems left in a heap overnight generates its own heat and moisture, and a batch that heats even once will not store well afterwards.

Hanging or racking the plants

The simplest method is to tie the cut plants in loose bundles of five or six by the stems and hang them upside down from a rail, a beam or a line of string. Upside down keeps the pods hanging clear, and loose bundles let air through the middle. A tight bundle of twenty plants will be dry on the outside and damp at the core, and the core is where mold starts.

If you would rather not hang them, spread the plants in a single layer on an old sheet, a tarpaulin or a rack of wire mesh, and turn them every few days so the underside gets its share of air.

Either way, put a sheet or tarpaulin underneath. Pods will split during curing, that is expected and it is why the crop is under cover, and the beans that fall are perfectly good. Curing over a bare shed floor means sweeping them out of the corners afterwards.

1. Bundle loosely, five or six plants Tie by the cut stems with string. Loose enough that you can see daylight through the middle of the bundle when you hold it up.
2. Hang upside down, clear of the wall Pods should hang free with air on all sides. Bundles pressed against a wall stay damp on that side and mold there first.
3. Lay a sheet underneath Catches the beans from pods that shatter during curing. Those beans are ready to store and should not be swept off a dirty floor.
4. Check for mold in the first week Look at the center of a bundle after four or five days. Any gray fuzz or musty smell means untie everything and spread it out in a single layer immediately.

Testing whether the beans are actually dry

Judging dryness by eye does not work, because a bean that looks and feels hard can still hold enough moisture to spoil in a sealed jar. There are two reliable tests and both take seconds. The first is the bite test: bite a bean firmly. A properly dry bean shatters or cracks sharply and hurts your teeth. One that dents, splits softly or feels at all chewy needs more time.

The second is the hammer test, better for a large batch and safer for your teeth. Tap a bean on a hard surface with a hammer: a dry one shatters into fragments, an underdried one flattens. Test five or six beans from different bundles, because a batch dries unevenly and the middle of a bundle lags behind the outside.

For the borderline case, put a handful of beans in a sealed jar somewhere warm for a day. Condensation inside the glass means there is still moisture in the beans and the whole batch goes back to dry for another week.

When in doubt, dry for another week. There is no way to rescue a jar of beans that has molded, and nothing at all is lost by over-drying.

Threshing and winnowing

Once the pods are brittle, getting the beans out is easy. Put the dried plants into a clean pillowcase or a tough sack, close the end, and either tread on it, beat it with a stick, or roll and twist it firmly. The brittle pods break open and the beans collect at the bottom. Small quantities can be rubbed out between your palms.

You are then left with beans mixed with pod fragments, stem and leaf, which is where winnowing comes in. Pour slowly from one bucket into another in a steady breeze or in front of a fan on low. The beans drop straight down and the light debris blows sideways. Two or three passes gets you clean beans.

Sort the clean beans by hand before storing. Discard anything shriveled, cracked, spotted or holed: a holed bean has a weevil in it, a spotted one may carry seed-borne disease. Twenty minutes here is the difference between beans that keep and beans that develop a problem in the third month.

1. Wait until the pods are brittle A pod that bends rather than snapping is not ready to thresh, and threshing early bruises the beans and drives moisture back into them.
2. Thresh in a bag Pillowcase or sack, closed at the end, then tread or beat it. Keeps every bean contained and takes a few minutes for a garden-sized crop.
3. Winnow in a breeze or in front of a fan Pour slowly between two buckets from about waist height. Beans fall, chaff blows away. Repeat until only beans are left.
4. Hand-sort before storing Remove shriveled, cracked, spotted and holed beans. Small round holes mean weevils, and one infested bean spreads through a whole jar.

Storing, and what a soybean needs before you eat it

Fully dry, clean beans go into airtight glass jars or sealed food-grade tubs, kept somewhere cool, dark and dry. Stored properly they stay in good eating condition for two to three years and remain safe to eat for considerably longer, although they take progressively longer to cook as they age. Label every jar with the year, because dry beans of different ages look identical and cook very differently.

Put the sealed jars in the freezer for a week before shelving them, which kills any weevil eggs that came in with the crop. Let them come back to room temperature fully before opening, so condensation forms on the outside of the glass and not on the beans.

Raw soybeans must not be eaten. They contain compounds that block protein digestion and cause serious stomach upset, and unlike many beans they are not palatable raw in any case. Preparation means soaking overnight in plenty of cold water, discarding that water, then boiling hard in fresh water for at least an hour, often closer to two, until a bean crushes easily between finger and thumb. Do not shortcut the boil, and do not taste-test raw beans from the storage jar the way you might with peas.

Keep a portion aside as next year's seed, stored the same way but labeled separately, taken from your best plants and never from anything that showed mottled or puckered leaves. Note the year on the seed jar too: germination falls away noticeably after two years, faster than most vegetable seed.

Write the harvest year, the total dry weight and the drying time on the jar label. Two seasons of those labels tell you whether your curing space is quick or slow and how much room to give the crop next spring.