I am having a hard time imagining what you are talking about. Got a pic? It would also help if you said which varieties you are growing.

Rodney

Same here. Not sure what you mean. Are you talking about the core?

Dave

Hi Dave, yes that's it. What happens with some of my tomatoes, the stem seems to grow down much more then in this pic, often half way into the body of the tomato and as solid looking as it is right at the top. However, I don't notice a bad flavor. I've been removing the white part but that can mean removing a lot of the tomato meat. Last night I made a pizza with fresh tomatoes and found this interior stem in 4 out of 5 tomatoes I chopped up. I don't have a pic right now but will try to post one later.....

That is the anchoring mechanism and that is how the fruit stays on the stem.

Also it is like a root system delivering the food and nutrients to the fruit. JMO

Sey

"Is it environmental or genetic?"

Both variety and cultural. The more oblate the tomato and recessed the stem into the stem end the more the varieties seem to have this problem, the rounder the less. The colder the night time the worse it is, and a cool period followed by a very hot one causes it too. Others blame over-fertilization in the early stages of fruit set.

Cheers

PC