Depending on where you live, you may have seen raccoons going through your trash can on a regular basis, so it’s odd to hear that they are conscious about washing their food.
With a water source nearby, a raccoon will dunk its food into it vigorously multiple time, rotating it to get all the dirt out. At least that’s what it looks like from the outside. There’s one thing that makes impossible to know if the purpose of this action is to actually clean the food: raccoons have been seen “dunking” their food in the air, as well, if there’s no water source visible.
Why do they do it then? No one is sure. It may have something to do with the tactile part of a meal, as raccoons have sensitive fingers so it may just feel nice to perform this ritual.