Whatever happens now, make sure you are not scared around her. Be very calm. If you get anxious and scared of her, she will pick up on that, and think there is a reason and need to be on alert, and will be more likely to bite again.
It might be you need to make adjustments so that this doesn't happen again, and basically so you are starting to work within her means and limits. It might mean wearing gloves, it might be that you need to feed her in a different way (maybe scatter feeding, or take the bowl out, refill and put it back, or it might be that you need a different type of food bowl, or maybe a treat ball would work well for her, and if you have two, you can just put a full one in, and then later remove the empty one).
It could be that she is not spayed, it could also be that because she is a foster bun, she has a history, and no one will really know what that fully was, and it may be her hisotry is making her react in this manner around food (like if she was deprived of food, or teased with food, or something). Just be patient and keep working with her.