Collecting tomato seed

A little know secret is how to harvest tomato seeds. 

Tomato seeds are enclosed in a gel sac; to remove the sac and to help destroy seed-borne diseases, you have to put them through a fermentation process:

1. Wash the fruit, and then cut it in half across the middle (not the stem end). Gently squeeze seeds and juice into a labelled glass or plastic container. Fill containers about half full, and then set them out of direct sun in an area where you won't be bothered by the ripening odour or fruit flies.
2. Allow the seed mixture to sit until the surface is partially covered with whitish mould (in three to five days). In warm climates, you may need to add a little water midway through the process to keep the seeds afloat. Scrape off the white mould with a spoon, being careful not to remove seeds.
3. Fill the container with water, and then stir; the good seeds will sink to the bottom.
4. Pour off and discard floating seeds and pulp. Repeat until the good seeds are clean. Pour the cleaned seeds into a fine strainer; rinse and drain.
5. Sprinkle seeds onto a plate and allow them to dry for one to three days, depending on the weather. Keep them out of direct sun. To make sure they dry thoroughly and don't stick together, stir twice a day. Store dried seeds in a cool, dry, dark place in individually labelled airtight containers such as glass canning or baby food jars until planting time next spring.