Mangoes that you purchase at the grocery store often need ripening to develop the best flavor. As with many commercial fruit varieties, mango growers harvest and ship the fruit before it fully matures to prevent damage during transport and prolong the shelf life. Hard mangoes will ripen on their own if you leave them alone at room temperature for three or four days or until the flesh yields slightly in a cool room. But if you can't wait to enjoy the sweet tropical taste, you can speed the ripening process of a mango.
Put the mango in a brown paper bag. The fruit releases natural ethylene gases that help it ripen. Trapping the gases around the fruit in the brown paper bag speeds the process. You can hurry it along even more by putting a small apple in the bag too.
Fold the top of the bag down two or three times and secure it with a paper clip.
Look at the mango after 24 hours. Many varieties turn a deep peachy-yellow color when ripe. Kent and Keitt varieties remain green, however.
Inspect the stem end. It should smell fruity and sweet and feel slightly soft to the touch. If it doesn't, put it back in the bag and check on it again in about eight hours.
Mangoes that are football-shaped are likely to have a better flavor than those that are flat or thin, according to Aliza Green, author of "Field Guide to Produce." Flatness may indicate stringy fruit.
Ripe mangoes stay fresh in the refrigerator for up to four days.