I read that you can put out libations overnight, and the next morning their essence will have been drained and you throw them out. I'm not sure I like the idea of throwing away food, though. Can I eat the libations after their essence has been drained? Is is bad cosmic manners or will it affect me in some way or...?
Most traditions which utilise offerings will advise you to never take back what you have given, you should never consume an offering which you have made.
Most traditions leave the offerings outside and allow wildlife to eat them (if it is safe for them to do so) they pour any liquid to the earth for the Earth to absorb it etc. You have offered it to a specific being, then the local beings get the leftovers.
Most traditions will also say not to throw offerings away- I personally do if the thing cannot be left for wildlife to eat and state that there is no disrespect meant in this action, rather I am simply concerned for the environment.