The grapefruit isn't a glamorous fruit, and it's something that people seem to eat (or drink) only at breakfast or when they're trying to lose weight (does anybody remember the grapefruit diet?). The fruit has a flavour that ranges from sharp and almost as acidic as lemon to sweet-tart. Season: although they're not as easy to find as other citrus fruits, grapefruits are in the supermarkets year-round. Varieties: many. Most of us, though, probably couldn't tell all the subtle variations between grapefruit varieties, and would classify them into three different types based on the colour of their flesh: white (actually, they're pale yellow), pink or ruby. The latter seem to be the sweetest and least acidic. How to choose: as with all citrus fruit, look for grapefruits that seem heavy for their size, which indicates they're full of juice. Storage: wrap them in plastic bags and store in the vegetable section of the fridge. What else? Grapefruits are related to the popular Asian fruit, the pomelo, which they strongly resemble (grapefruits are smaller, have thinner skins and membranes and they tend to be more acidic than the mild pomelo). In fact, it's believed that grapefruits are a hybrid between the pomelo and orange. If you're taking prescription or over-the-counter drugs, take care because eating grapefruit or drinking the juice can sometimes interfere with the potency of the drug. Check with your doctor. Nutritional content: grapefruits are low in calories and have high levels of vitamin C, vitamin A and fibre. How to prepare? Depending on the sweetness (or lack of) in the grapefruits you buy, the juice can be used in many recipes where you would normally use lemons or oranges, although you'll probably have to adjust the amount of sugar. Fresh grapefruit juice gives a lovely, unexpected flavour to vinaigrettes and other salad dressings. It also makes a refreshing sorbet or granita. Grapefruit peel can be candied, in the same way lemon or orange peel is. Cut the peel in thick matchstick pieces, blanch three times in boiling water (changing the water each time) to take away the bitterness, then simmer slowly in a strong sugar syrup until the peel is permeated with sugar. Dry the pieces at room temperature then roll in sugar.