Contrary to what Aquinas states, I think that there will, in fact, be food in Heaven, simply not the kind of food we are used to. After all, the risen Lord, I assume, did not dine with the disciples merely to show that he was not a ghost; he was demonstrating a real fact about what it is like to be resurrected. The supernatural effusion of divine grace into the resurrected body does not destroy the old, regular human nature but builds upon it.
As to the nature of this heavenly food, one can only speculate since we are dealing not with nature but with super-nature. The closest thing that comes to mind, of course, is the Eucharist, but since the presence of the Deity would be supremely effusive into everything in the New Heaven and Earth one might wonder if the Eucharist would be even necessary.
Or maybe it is, sort of? After all the whole point of divine grace is that it is wholly 'unnecessary' and gratuitous (the word 'gratuitous', of course, coming from the Latin gratic meaning, among other things, 'gift'). Maybe some kind of super-Eucharist or super-elf bread is the food of the blessed (and they don't have to worry about going to the bathroom, either, I would think), since the total union of the person to God, physically and spiritually, is the chief characteristic of living in Paradise, and consumption (but not digestion!) of the Deity is, I venture, a particularly intimate sort of physical union. Kinda gives a new meaning to those old Philly cheese commercials about having 'a little taste of Heaven in your mouth'.