
Basil syrup is a flavoured sugar syrup infused with fresh basil leaves, used as a sweetener and aromatic in drinks.
Green, peppery basil aroma over a full, sweet body, with the herb's fresh leafiness carrying through the finish.
Shaken into a build in small measures, it sweetens while adding a fresh-herb aroma, dosed to balance acidity without letting the sugar dominate.
Where basil is only a light accent, plain simple syrup restores the sweetness and body with modest loss; where the basil note is the drink's signature, only another basil preparation — muddled fresh basil with sugar syrup, or a basil-flavoured syrup — reproduces the defining aroma.
Makers steep fresh basil (Ocimum basilicum) leaves in a base sugar syrup — a concentrated solution of sugar in water — so the finished liquid takes its flavour and aroma from the herb. The result is a thick, viscous syrup holding a large amount of dissolved sugar with little tendency to crystallise.
As a fresh-herb infusion with no preservatives, house-made basil syrup is perishable; refrigerate it and use within days, as the aroma fades and it spoils far faster than plain sugar syrup.