I have seen, that many people use kitchen scraps for making broth (eg. onion root and scraps) or that they just crush garlic, but still keep it in its skin or that people even do not peel carrots.
I am using slow cooking, but when I would be using these 'leftovers', is not there a risk of bacteria (from garlic skin maybe)?
Is it recommended to bring it to boil every time for a while? And even if it is boiled, there can still be toxins, that do not breakdown by boiling.
So is there any advice concerning that? Is there a procedure, that should always be taken into consideration?