Found a clue I think from a separate space discussion. It's farts.
All space food is specifically made to be low FODMAP. FODMAPs = fermentable carbs (like lactose, fructose, polyols) that your gut bacteria love to munch on which leads to gas and bloating. NASA avoids these like the plague in space food. They opt for low-fiber, lactose-free, no-bean, low-sulfur meals to keep astronauts from turning the cabin into a Dutch oven.
If i had to guess I would say it likely comes down to how the rice and bean plants fair in low G. If they're eating real rice and fake beans I would think its because the rice is either grown on or near ceres as well as the yeast and fungus substitutes that make up the fake beans, whereas real beans would have to be imported in
I could see zero gravity making rice very space efficient to grow. Stacks on stacks of individual semi automated rice paddies