A pineapple will turn yellow if you let it sit for a few days after purchase. You may think that is the fruit ripening, but in reality, it's the fruit actually declining. The host of this video from MinuteFood explains that a pineapple will just get worse as you let it "ripen" on your counter, with disappointing results. And we get an explanation of why. In my experience, I don't recall ever being disappointed in the taste of pineapple, whether it's fresh from the market or old and yellow, but maybe that's just me. Some fruits will further ripen after picking, while others will not, and there's a way to remember which is which, but even then pineapple is an exception that we just need to remember. Now, if we could only tell how long a pineapple has been sitting in the produce bin, we'd be able to judge them better. By the time this video is through, you'll want to make a fruit salad with fresh pineapple. The video is only 6:30; the rest is an ad.