Blackberries are juicy, lustrous purple-black berries that are at the peak of season in summer. It is an aggregate fruit because they are clusters of one-seeded drupelets, each cluster of drupelets developing from a single flower. The drupelets are typically eaten as a cluster, and not individually.
The fruit is very dark purple with smooth, fragile skin. In the middle of the cluster is a greenish-white core that extends to almost the bottom of the berry. Blackberries can be easily confused with raspberries, but raspberries have a hollow center. Blackberries are red and hard when they are immature and turn black and shiny when they ripen. The blackberry is known to contain polzphenol antioxidants, naturally occurring chemicals that can upregulate certain beneficial metabolic processes.
Blackberries can taste too tart to eat out of hand until they have fully ripened. Blackberries are ripe when they go from glossy to dull, a transition that usually takes two to three days. A fully ripe blackberry has a melt-in-your-mouth quality. In addition to tasting sour, prematurely picked blackberries have less than half of the immunity-boosting anthocyanins found in ripe berries.
Blackberries are packed with antioxidants, including vitamin C and ellagic acid, which may provide protection against cancer and chronic disease. Their many tiny seeds make them a good source of fibre. They also contain salicylates, a group of analgesics that include the active substance in aspirin.