World Agriculture Info: Wet seed processing at DBF

Seeds!

We are now in the time of year that I’m calling “harvest”- not because harvest doesn’t happen before or after this time, but because much of our time is spent harvesting crops. The summer fruits (like tomatoes and peppers) are ripening with increasing frequency. In addition to edible crops, we’re doing a lot of seed harvests. I’ve described a few different methods of seed harvest and cleaning, but so far they have all been seeds that require a “dry” processing. I’ve now learned about seeds that require a “wet” processing.

We use wet seed processing for our tomatoes, melons, and cucumbers. These crops produce seeds that are enclosed in gelatinous sacks; the seed must be released from the flesh (using water- hence the term “wet”) in order for it be cleaned and dried.

Cucumber seeds in their casings

The process for wet seeding at DBF (with some recent photos) is basically as follows:

Step 1: Harvest crop at full maturity.

Green Apple cukes with mature seeds

Step 2: Remove seeds (with attached flesh) from the fruit. In melons and cucumbers, this involves cutting them in half and using a spoon to scoop the seeds out. In tomatoes, this involves smashing the tomatoes by hand to release the seeds from the inside.

Scooping seeds out of Rich Sweetness melons

Scooping seeds out of Green Apple cucumbers

We use a bat to smash Sun Gold tomatoes

Step 3: Mix seed-pulp mixture with water in a tall bucket.

Step 4: Let the seeds sit in the juicy water. Over time, this mixture of flesh and water will ferment and eat away at the gel casing surrounding the seeds. Tomatoes ferment for a few days, while melons and cucumbers ferment for about one day. Viable seeds will sink to the bottom of the bucket, while nonviable seeds will float to the top.

Tomatoes get a crusty, moldy layer when fermenting (the fruit flies love it)

Step 5: Pour the water, nonviable seeds, and other residue out of the bucket. When poured out properly, the viable seeds will remain at the bottom of the bucket and everything else will drain out. This process normally takes multiple pours, refilling the bucket with water each time.