What you see: White and green squiggles in tomato flesh
What it is: Sprouting tomato seeds!
Eat or toss: As long as the tomato is intact and not showing signs of rotting, etc., it’s entirely safe to eat them. Some say such tomatoes might not taste as good and should be used in cooked dishes, but I’ve eaten them raw and haven’t found the flavor to be off. It probably depends on how much the sprouts have grown.
We knew this tomato was not long for this world. We were rushing to use it up when we sliced it open and discovered....it was pregnant?
Ok, that’s not really how it works in plant world, but this tomato really was starting to grow baby tomato plants right inside itself. The seeds germinated while still inside the parent plant, splitting open to reveal eager green sprouts. The phenomenon is known as “vivipary” which actually does mean “live birth.”
Why did this tomato’s seeds start unleashing those wormy looking sprouts? First off, it was an older tomato. The hormone that prevents seed germination was probably running low. Second, the tomato was on the counter in my too-warm apartment, where an outdated heating system often creates sweltering indoor weather in January. That high temperature, along with the moist conditions deep inside this tomato, created an ideal germination climate.
So, now that we know what’s going on, there’s the question of whether you should eat these wormy slices. You may be inclined to avoid them because a) they look weird and b) you’ve heard that the green parts of tomatoes carry a toxin similar the toxin that makes very green potatoes unsafe to eat. But, luckily, there’s no need to worry about any harm from those little green tomato sprouts. The substance in question here is tomatine, which is also present in the underripe green tomatoes that are fried in that famous Southern dish, and has not been proven to be particularly dangerous to people, especially in normal-sized quantities. Harold McGee does a great takedown of rumors of toxic tomato parts in the New York Times.
In assessing whether you should eat a viviparous tomato, you'll also want to do a close inspection for rot or mold — given the age of the tomato, they're both more likely.
This tomato didn't have signs of squishy rotten tissue, or spots or fuzz that would indicate fungus, so I ate it and didn’t notice any taste difference. According to Extension.org, tomatoes with sprouted seeds may not taste as good, so they may be best used in cooked dishes. If you encounter one of these wormy delights, my suggestion is to just sample it and make your own call.
I cut into a locally grown tomato and all the seeds inside the tomato were sprouting -- Extension.org
Seeds sprouting inside a tomato - University of Connecticut Extension
Vivipary - Free Dictionary.com
Accused, Yes, but probably not a killer - New York Times
Abscisic Acid - McDaniel College