Grapefruit provides a variety of important nutrients in one convenient package. It has an ample supply of pectin, the soluble fibre that is effective in lowering cholesterol levels, and of potassium, which is important in controlling blood pressure. This familiar member of the citrus family is even more highly valued as a source of vitamin C: These attributes, along with its refreshing tart flavour, juicy texture, and low calorie count, have made grapefruit a popular breakfast food.

Grapefruit probably developed from a cross between an orange and a shaddock, a citrus fruit with thick skin, many seeds, almost no juice, and a very sour taste. But skillful growers dramatically improved the flavour and texture of grapefruit, beginning with the development of seedless varieties nearly a century ago. The result is a citrus fruit that combines tanginess and sweetness.

Indigenous to the West Indies, grapefruit became well established in Florida in the early 1800s: Today, 80% of the U.S. crop and half of the world's production is shipped from that state.

Buying
Since grapefruit is not picked until fully ripe, you never have to worry about getting a "green" one. Under certain growing conditions, the lemon yellow skin may revert to green after it is ripe, but the fruit will lose none of its tangy sweetness.

Look for round, smooth fruits that are heavy for their size (they will be juicy). Coarse-skinned grapefruits or those that are puffy, soft, or pointed at one end are inferior; glossy fruits with slightly flattened ends are preferable. Gray-brown "russeting" or other skin defects are superficial and do not affect quality. At room temperature, you may be able to detect a mildly sweet fragrance, but it will not be apparent if the fruit is chilled.

Storage
Grapefruits can be left at room temperature for a week, and are juiciest when slightly warm rather than chilled. For longer storage, they should be held in the refrigerator , where they will keep for six to eight weeks. Leave them at room temperature for a while before you juice them or eat them.

Preparation
Rinse grapefruits before cutting them. For serving from the "shell," halve grapefruit crosswise. Use a grapefruit spoon with a serrated tip to scoop out the sections, or prepare the fruit using a sharp paring knife or a curved-blade grapefruit knife, running it between each segment of flesh and the membrane "dividers." (Grapefruits, like other citrus fruits, may be called "seedless" if they contain no more than five seeds, so don't be surprised if you have to remove a few seeds.

You can also peel a grapefruit as you would an orange; use your hands or pare the skin with a sharp knife: Slice a disk of peel from the top, then pare slices downward around the fruit; or, pare the skin in a spiral, as you would an apple. Then pull apart the segments with your hands and, if desired, remove the membranes from each segment.