A pineapple is ripe when at least one-third of the rind turns yellow. Green pineapples may be ripe if they are full-sized and the "eyes" are large and flattened.
Ripe pineapple is plump and firm. The crown leaves are spiky and green. Tapping on an unripe pineapple makes a hollow sound, while ripe pineapple sounds solid.
As a pineapple ripens, the color changes from the bottom up. It smells fruity, and the pulp is yellow and juicy. If the pineapple smells sickly sweet, it is overripe. Mature fruit lasts in the refrigerator for about a week. Pineapples do not continue to ripen after they are picked.