MELONS
First off, we need to get over the idea that all melons can be thumped. The only melons you should be thumping are watermelons. They're still kind of touchy, but the ones with a slight indentation where the stem connects are usually sweeter.
Cantaloupe-Smell where the stem connects to the melon. It should be sweet and cantaloupy.
Honey Dew-You'll get stared at with this one, but it works. Shake the honey dew next to your ear (don't hit yourself in the head), you should hear the seeds rattle. This works for crenshaw melons as well.
CITRUS FRUIT
Grapefruits, lemons, oranges, tangerines-Look for fruits with a thin, soft skin. If it's thin and hard, it's old.
Pears
Nothing is quite as lovely as a perfectly ripe pear. Lots of people complain that they don't like pears because they are mushy. Guess what, mushy pears are overripe. A ripe pear should be firm, yet giving and juicy, NOT woody. To pick a pear, hold it upright and gently press the flesh closest to the stem.
Like so:
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If it gives slightly it is at the peak of ripeness.
Cucumbers
Cucumbers should not be mushy. That's just gross. Gently squeeze the ends of the cuke, it should be firm. Cucumbers age from the ends to the center. If your tips are mushy it's only a matter of time before your core spoils.
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Cilantro
Don't sniff the leaves of the cilantro! Instead, smell the cut ends. It should be strong and pungent.
Pineapple
If you go to the Dole plantation in Hawaii, they will tell you that you don't need to worry about selecting a ripe pineapple. All Dole pineapples are fresh and ripe on the shelf. However, should you have to buy a different brand of pineapple, smell the bottom. It ought to be sweet and pineapply. If it has even the slightest scent of mold or fermentation--drop it like it's hot. Well, unless you're planning on making pineapple liqueur. If your pineapple has uniform eyes, it indicates that it's had sufficient and even watering. Pulling out a leaf is a wives tale.
Happy shopping!
Oh and rutabagas should be firm. Just FYI. ;)