Ranging in color from dark-red to black, juice from wild-growing blackberries is sold by several companies. If you have any trouble finding it in your local market, try the health food store (always a good place to find interesting juices).
You can use blackberry juice as a substitute for blackberry liqueur, should you want to keep your drink alcohol-free. The juice has the same sour-fruit taste you’ll find in blackberries themselves.
Making Your Own Blackberry Juice
Pick a firm, bright, dark berry for the sweetest flavor. Use the berries as soon as possible, but while you wait, put the berries in containers or plastic zippered bags and squeeze out as much air as you can.
There are many recipes for making blackberry juice, but the easiest method takes only ten minutes of preparation time and eight minutes of cooking time. You can also substitute two 16-ounce packages of thawed frozen blackberries if fresh berries are not available. To make two cups of juice, use two quarts of fresh cleaned blackberries and 1/2 cup water. Bring to a boil in a three-quart saucepan. Reduce heat. Simmer for five minutes or until the blackberries are soft. Mash blackberries with a fork or potato masher. Pour through a large strainer into a bowl. Use the back of a spoon to squeeze out the juice. Discard the seeds and pulp. Sweeten with sugar or honey to taste.