Thick-walled plum tomatoes hold up the best during the preservation process and can provide surprising health benefits that even fresh don’t offer. Tomatoes are preserved using heat, which releases lycopene—a carotenoid that may help prevent prostate and breast cancer. And you can’t beat their convenience. They come whole, diced and crushed (to name just a few renditions), so you can skip all the chopping and pureeing you do when using fresh.