
Blackberry purée is a non-alcoholic fruit purée of blackberry pulp reduced to a smooth, thick mass.
Fresh berries blended and strained is the same thing made to order, and straining is not optional unless you want seeds. Another dark-berry purée gives the same body and acidity and changes only the fruit. Syrup or liqueur brings flavor and color with sugar and no body at all.
Blackberry juice
Strained clear of solids, so it colors and sours a drink and adds nothing to the texture; swapping juice for purée leaves a sour that will not hold its head.
Sweetened fruit purée
Bar-supply bottles usually arrive with sugar already in them. Cut the recipe’s syrup by roughly what the label declares, and taste before you pour more. Using it in a recipe that expected unsweetened puts the drink out by a barspoon of sugar or more.
Fresh purée keeps a few days refrigerated and freezes well, which is the honest answer for something used a spoonful at a time. Freeze it in portions, because thawing and refreezing the tub turns it watery.