Are there any foods a fox will eat but a raccoon will not?

For well over a year, I’ve been putting out “gifts” for the neighborhood fox family. They are beautiful animals and they’re neat. I usually place the food out before it gets dark around 7 PM. At the same time I put the flash card in the trail camera so I can watch the invisible, nightly action.
I only put out about 600 calories worth of food (about half the daily caloric requirement of one fox) so they must still hunt to survive. The food is a treat on days when I do not leave a chipmunk, squirrel or a couple mice. The fox always takes everything away and never leaves a mess: no bones, no fur, no poop – the ideal dinner guest.

Here’s the problem. For the past week or so a family of racoon have moved in and are getting to the food before the fox. The camera indicates they show up around 8:30 and clean the pans out in about 2 minutes. They tear stuff up and leave bones, droppings, and generally leave a mess. Last night I went out at 9:30 in total darkness and heard the fox calling in my orchard about 50 meters away. It sounded exactly like this . Really terrifying if you don’t know what it is. Pathetic if you do.

I’m looking for some food that I can leave out that only a fox will eat and a raccoon will avoid. Do you have any suggestions?

I am trying to avoid the easy “nuclear option”.