I have made liqueurs for many years, using different methods:
- Adding a concentrate to a base spirit
- Adding various ingredients to a base spirit
- Steeping fruit in a base spirit
Concentrates are the easiest — put the concentrate, sugar syrup, glycerin, and base spirit in a blender, and blend. In the past I purchased flavorings for brandy and made my own Apricot and Cherry brandies, which came out good.
Following a recipe is second easiest, although it best to review recipes carefully as not all are good. I’ve tried several for Amaretto, and the ratio of flavorings made a big difference.
Steeping fruit takes the most time — I’ve made Limoncello (lemons), Limecello (limes), Cherry Cognac (cherries), and Orangecello (oranges). Stronger spirits such as EverClear shorten the process and extract more from the fruit, but because it’s so strong, I had to use Pearson’s Square to figure out how much sugar syrup to add to get to 30% ABV (60 proof) and how sweet to make the syrup so that it’s not overly sweet.
Note on glycerin — I add glycerin to all liqueurs, as it smooths any raw alcohol flavors and adds mouthfeel.
Note on base spirit — different liqueurs need different spirits. For Limoncello and Limecello I used inexpensive vodka, but have switched to Everclear 151 (190 proof is not available in my area) as it extracts better. Brandies use inexpensive brandy and cognac based liqueurs use (you guessed it!) cognac. I note a different taste between American brandy and cognac, and while they can be interchanged, it will alter the flavor.