Take a fully ripened tomato and cut it in half. Scoop or squeeze out the seeds and juice into a small, labeled container. If done carefully, the tomato itself can be saved for eating, sun-drying or canning.
Add a little water to the container so that the seeds can float, then loosely cover it and set it in a warm place for 3-5 days where the odor will not bother you. Stir or swirl the mixture once or twice a day. The seeds will ferment and mold will grow at the surface. This mold is your friend; it eats the gelatinous coat around the seeds that stop germination. It also produces antibiotics that prevent disease.
The viable, mature seeds will sink to the bottom. Pour off the excess water and solids at the top. Add more water and repeat this step until the seeds are clean and the water being poured off is almost clear.
Spread the seeds onto a paper towel or plate and let them dry for 1-3 days. Keep them away from direct sunlight. Stir them to make sure they do not dry in clumps.
Store the seeds in a dark, cool place in an airtight container. Don’t forget to label them with the name, variety and date you saved them!
From a newsletter from: www.freshthemovie.com
Toms Blog on Life and Livingness