Blackberry

Look at a blackberry before you touch it. The colour tells you a lot. A fully black berry, with no red or green drupelets left, is ripe. A berry with even one red or green drupelet is not ready, and it will stay sour no matter how long it sits in your fridge — blackberries don't sweeten after picking the way some fruits do. Press it gently. It should give, soft but not collapsing, with each drupelet plump and full. Pull it from the stem: a ripe one comes away easily, core and all, while an unripe berry clings stubbornly to the cane.

Smell it too. A ripe blackberry smells sweet and fruity. If you're still unsure, taste one — that tells you more than any other sign.

Some people say the shiniest berry in the basket is always the best one. No! I've bitten into a glossy berry and found it sour, and into a duller one and found it sweet right through. What never lies is the give under your thumb, the ease with which it leaves the stem, and the smell under your nose. Chase the shine alone, and you'll fill your basket by looks, picking berries that catch the eye but disappoint on the tongue — a mistake you only discover after the jam is already on the stove. Trust your fingers for give, your nose and mouth for the final word, and let colour be just the first glance, not the last.