Yellow-orange on the outside and bright red in the middle, ruby red grapefruits are sweet/sour to taste. They are round, seedless and about the size of a softball. Storage These grapefruits can be stored at room temperature for a week or up to two weeks in the fridge. Nutrition Grapefruit have a fat burning enzyme that makes them great for weight loss. Ruby red grapefruit are also an excellent source of Vitamin C ? just half a grapefruit provides 80% of an adults daily needs. Grapefruits are high in dietary fibre, contain no fat and can help lower bad cholesterol. Ideal Use Cut into wedges, a ruby grapefruit can be eaten much like an orange. It is also great cut in slithers on top of a salad.