Considering the food thread has been going for months (maybe even since last year... can't remember exactly when I started it) and it only has four pages, and since there are only a couple of food-related threads, I don't think there's a huge call for such a thing.
In my opinion, a good way of looking at whether or sub-forum should be added is to ask "Are there a lot of threads of this sort cluttering a section of the forum?" If the answer is "yes," then we probably need a sub-forum for it (this is what happened with
betta breeding). If the answer is "no," then we probably don't need one (yet).