I suggest only storing leftover quinoa and brown rice, not the porridge. After you mix in the almond milk, it will change the consistency of the grains and make them mushy. This might not be appetizing the next day. Instead, store the brown rice and quinoa in the refrigerator in an airtight container for up to 5 days. Then, when you are ready to make more porridge, grab it from the refrigerator and heat it up with the rest of the ingredients.