||I'm not sure why you're questioning something that has been done for many years, but look at the Gemara, Rambam, Tur, Shulchan Aruch, Mishna Berura, etc. Check it out.
If you find a source that says one cannot put up any raw food right before Shabbat, please let me know. It is even said, according to most, that you can add raw meat to a partially cooked pot and it would be muttar without a blech
Your question is a bit vague..