Hi! I am relatively new to canning, and working on tackling tomato sauce.

When I am making sauce to eat right away or freeze, I always leave the peels and seeds on. I know that when I am canning I have to remove the peels, cores and seeds. I did that both times I made sauce. However, it seems like I am wasting an awful lot of the tomato. Does anyone have any advice for ways to use the cores/peels/juciy parts that get sucked out? How much of the tomato should I be using when I core? Does anybody ever use the seeds/cores for things like vegetable broth?

Thanks so much