Step three of Farm Radio International's Starting a Community Seed Bank is cleaning and drying the seed. It is recommended that "once the seed is collected, carefully prepare it for storage. Store only the seed. Sift or winnow chaff or dirt from the seed using a basket, or remove seed from cobs or pods by hand. Farmers may leave seeds on their cobs or pods to protect them from mould or insects. Follow local customs."
"Most seeds must be dried before they can be stored. Spread seeds to dry in a warm place, but not in direct sunlight. Test the dryness of a seed by bending it between your fingers. If the seed breaks, it is dry enough. If the seed is springy but not breaking, the seed is still too moist. Be careful to keep seeds dry, especially in the rainy season. Moisture in the air will make the seeds mouldy. Seeds from certain tropical fruits such as coconut, mango, and orange should not be dried, but should keep their natural moisture. Plant these seeds as soon as possible after collection. You can keep this type of seed in a plastic bag which is opened once a day so that air mixes with the seeds."
Farm Radio International recommends not to dry eggplant, tomato, squash, and melon seeds. "Put the pulp and seeds into a full pail or pot of water. Do not put too many seeds in the pail, or the bad seed will not be able to float to the top of the container. Let the seeds sit. Stir them occasionally for three to five days. The bad seed will rise to the top of the water, and you can throw them away. The good seed sinks to the bottom of the pail. Dry this good seed for 2 to 3 days before it is stored."
Information Source: Farm Radio International, "Starting a Community Seed Bank," Package 33, Script 4, July 1994.