Here's why you should buy bananas partly green

Bananas should be fully yellow without brown spots. They ripen fast, so buy them partly green. Contrary to popular belief (and despite the original "Chiquita Banana" jingle), you may refrigerate them after they've ripened. Their skin turns dark in the cold, but inside they are still good.

Grapes can be judged for freshness based on the condition of the stem. When the stems look like dried-up sticks, their harvest was in the distant past. Buy grapes that are firmly attached to nice green stems. Avoid soft or wrinkled grapes and those that are leaking (a sign of decay). They don't ripen after harvest, so refrigerate after purchase or serve soon. Kiwis ripen well, but slowly, so buy them nearly a week before you use them. Buy them plump and firm but not rock hard. When kiwis yield to gentle pressure, they are ready. Once ripe, they spoil fast.

Watermelons that produce a hollow sound when thumped are best. Turn the melon until you find a light spot where it sat on the ground. If yellow, the melon is ripe, if white, leave it behind. Once cut or ripened, watermelon should be refrigerated and eaten within a few days.

Peaches and nectarines ripen and spoil fast. Growers must ship them while they're hard. Make sure they have no soft brown spots, and ripen them for a few days. Once ripe, their shelf life is short, even when chilled. Buy in small quantities and eat quickly.

Pears should be purchased when they are firm, but they will ripen fast in your kitchen. When you feel a slight give as you gently squeeze them, they are ready to refrigerate or serve.

Pineapples don't ripen off the plant, so those picked green with little sugar development will remain tart and flavourless. Try to find pineapples that are bright yellow, not too hard, and have a sweet scent. Look for a plump, heavy fruit. Avoid ones that have a dull colour, dry or brown leaves, or an overall dried appearance.