re: canning leftovers

Most foods will not be able to be safely canned if they are leftovers. Only recipes that are designed for canning and come from reliable sources should be canned. There is no way to know the ph level of your own recipes. Canning recipes are based on ph level, density, etc.and need to be followed exactly for safety against food borne illnesses, including botulism. Ball Blue Book of Preserving or the USDA publications are safe to follow. Also, your local county extension office will be able to provide you with tested methods and recipes. There are many ingredients that are not safe to can. Nothing with any starch,thickeners, dairy, eggs, rice, pastas, etc. is safe to can. The only thing with thickeners that may be safely canned are pie fillings using a special product called Clear Jel or jams and jellies.
Freezing is your safest method for preserving leftovers.