The brisk flavor of grapefruit will really wake you up in the morning.
Fortunately, it is not difficult to find acceptable grapefruit at the supermarket. That's because ripeness is not an issue. In fact, a ripe grapefruit can continue to hang on the tree up to a year after full maturity without any deterioration in quality.
Since grapefruit are always ripe and ready to eat when you purchase them, what you should be looking for is signs of flavor and juiciness. A juicy grapefruit will fee heavy for its size, since it is full of juice. The grapefruit should be firm, not soft.
A thin-skinned grapefruit is usually preferable to a thick-skinned one. A grapefruit that comes to a point at the stem end will usually have thick skin. The appearance of the skin is not important, but soft patches may be signs of decay.
Once home, grapefruit last longest in the refrigerator. Place the fruit in a perforated plastic bag in the warmest part of the refrigerator. The grapefruit should last up to two weeks. If stored at room temperature, the grapefruit will last about one week.
A cut grapefruit should be tightly wrapped and placed in the refrigerator. It should last two to three days.