Ed: The following halachos relates to the proper respect we should give food. Honestly, I do not know how aware of, or adherent to, these practices everyone is, nor do I have clear guidance on this topic from my teachers. I write them here because they are in our sefarim - one of our greatest sources for halacha!
9) It is forbidden to throw bread away, even in a place where it will not become repulsive, because the very act of being thrown away is degrading to bread – the staff of life. Regarding other kinds of foods, if they will become repulsive when thrown away, they should not be. Foods that will not become repulsive, such as nuts and the like, may be thrown away. Do not sit on a sack that contains fruits, because they will become repulsive. Do not wash your hands with wine or other liquids, because it degrades the liquids. (Ed. It seems to me that here we are speaking of washing for cleanliness. Regarding Netilas Yadayim before a meal, see MBY 160:12 Which liquids are fit for Netilas Yadayim?) When you see food lying on the ground, pick it up! Food that is fit for human consumption should not be fed to animals, because it is degrading to the food. (Footnote 2: If you have no other food for them, it is permissible. Mishna Berura 171:11)
10) If you have to make a medicine from bread or from any other food, even though the food will become repulsive by it, it is permissible.
11) Be very careful even with crumbs, not to throw them away. Our Sages taught that one who throws away crumbs brings poverty upon himself. Rather, they should be gathered and feed to the birds. (Ed: My father - may he live and be well till 120 - always gathers the crumbs from the challah tray on Shabbos and eats them! Beware, feeding birds on Shabbos may be prohibited!)
To be continued…