Once a pineapple is picked, it will not ripen any further. However, fully ripe pineapples are too fragile to ship, meaning they're picked before their prime. So your goal is simply to choose the ripest pineapple available. You can follow a few steps to tell if a pineapple is ripe at your local produce market.
Choose pineapples from Hawaii over pineapples from Honduras, Mexico, Costa Rica, the Dominican Republic and Puerto Rico. Hawaiian pineapples arrive in the stores two to four days after harvesting. The trip for pineapples from other countries generally takes four days to two weeks.
Look for a bright yellow-gold color when choosing a ripe pineapple. Ideally, that's the color of the whole fruit, but there may be some green. The further the yellow-gold color goes up from the base of the fruit, the better. Just be sure to never select a pineapple that is completely green.
You can tell if a pineapple is ripe by the smell at the base of the fruit. You're looking for a mild pineapple aroma as opposed to the smell of fermentation.
Squeeze the pineapple to make sure it's firm, but also soft enough to yield slightly to the pressure of your fingers.
Look for signs of deterioration. Avoid pineapples with wrinkled skin, reddish-brown skin, cracks or leaks, mold or brown withering leaves.