To choose a butternut squash, "look for smaller squashes since they are sweeter (this was actually tested by Cook's Illustrated)," says DougRisk. "Also, look for butternut squashes that are longer than they are round at the bottom...this way you are getting a smaller seed pocket and more edible flesh."
Mangoes are ripest "when they look somewhat 'old' (i.e. more spots and less sheen to the skin)," Doug adds. "This includes being shriveled at the stem end. The feel will also be less firm."
For onions, says Doug, "Press your thumb against the stem end and feel for the 'give.' The less 'give' the onion has, the fresher it is. That is, the onion 'rings' are more tightly packed."
To choose a pineapple, some folks test ripeness by tugging at the leaves at the center of the pineapple, but "If other people have already been plucking center leaves, that test is useless," says greygarious. "Look for the ones with the greatest pinkish blush. A ripe pineapple has a heady, sweet aroma when you sniff the stem end. If it only smells slightly, keep it at room temp until the aroma develops."
For Granny Smith apples, "If you like them very tart and very crisp, pick shiny dark green ones with lots of white freckles," says greygarious.
"At a peach farm once, the farmer's wife told me to always check the stem area when picking peaches," says eamcd. "If it's green or greenish-yellow, it was picked too soon. If there's a nice blush on the skin and the area around the stem is fully yellow, it was picked ripe enough. It's rarely failed me yet!"
Discuss: Pick-a-peck: produce pointers