I am led to believe that challah is a sacrificial bread. Does this mean it can only be eaten on Shabbos? Does it make any difference if it has been put on the Shabbos table and is now leftovers? I am talking about whole challahs
In Jewish terminology the word “Challah” has two distinct definitions. The first one is, that there is an obligation to tithe any dough, that is larger than about 2lb. 10 oz., and to give that tithe to kohen. Nowadays, that all the kohanim are ritually impure we don’t give it to them, but burn it instead.
Another colloquial use of the word challah is a way of describing the bread that we eat on Shabbos and festivals. The reason the bread eaten on these days is called this way, is because for technical reason it is forbidden to separate the Challah the on the Sabbath or festivals. Therefore, in order to remind ourselves to take this tithe before the Sabbath, we call the Sabbath bread challah.
Therefore, if you bake your own challahs for Shabbos, remember to separate the required challah. Then you can eat them on the Sabbath and during the next week, without any concerns, whether they are whole or in pieces.