I was talking with a person about getting all my green tomatoes in and ripening them for one last batch of sauce. She told me as a matter of safety that you shouldn't use tomatoes that were picked green for any sauce but couldn't explain why. It was just something she was told and and that's what she does. Is their any credibility to this? I usually just let everything ripen on the vine but we have a lot and the squirrels are beating us to most of them now as temperatures are getting lower.
I've never heard that. I have picked end of season tomatoes when they were green and let them ripen and used them for any purpose that I would normally use ripe tomatoes. And I know others who do also. It's much better than losing them to a frost or to animals.
If there is any downside, it would be that they might not be as flavorful as vine-ripened, but that still beats losing them.
Also consider that most of what we get in grocery stores come from large farms where they are picked green.
Just for the sake of saying it, many stores now also sell vine-ripened or locally grown tomatoes but they do cost more.
Yes, when they are not ripened on the vine, the acid level is lower (more basic) and therefore less safe for canning. If you will use the sauce right away no problem. Freezing the sauce would also be safe.