
Blueberries are small round berries with deep blue-purple skin and pale flesh, mild and only lightly tart.
Any dark berry covers the sweet-tart weight. A syrup adds sugar, which the recipe then has to subtract elsewhere. A frozen berry keeps the flavor, the acidity and the color, and gives up the shape and the fresh top note.
Frozen blueberries
They muddle far more easily, having burst as they froze, and release more color for the same reason; the fresh aroma does not survive freezing.
Blueberry syrup
Cooked and sweetened, so it stands in for the flavor and the color but never for the texture of crushed fruit, and cut the drink’s own syrup when you use it.
Ten days to a fortnight in the fridge, unwashed until the moment of use — water sitting on the skins is what starts the mold. Choose firm berries with the pale bloom still on them; the bloom is the fruit’s own wax, and a wrinkled berry has already given up its juice.