Cane syrup — sirop de canne in the French islands where it matters most — is pure cane sugar dissolved into a rich, heavy syrup, traditionally two parts sugar to one part water. It is the sweetener of Martinique and Guadeloupe, the third ingredient in a Ti Punch, and the reason a Ti Punch made with plain simple syrup tastes thin and wrong. Where simple syrup is neutral sugar water, cane syrup carries the faint molasses and grassy edge of the cane itself — the same plant the rhum agricole beside it was pressed from.
Cane Syrup Versus Simple Syrup
The two are not interchangeable, and the difference is twofold. First, concentration: cane syrup is a rich syrup at roughly 2 : 1 sugar to water, so it is nearly twice as sweet by volume as 1 : 1 simple syrup — a quarter-ounce of cane syrup sweetens what a half-ounce of simple cannot, which is exactly why a Ti Punch needs so little of it. Second, character: made from unrefined or partly-refined cane sugar, it keeps a trace of the molasses that white sugar has stripped out, giving it body and a low caramel note that white-sugar simple syrup lacks entirely.
Commercial sirop de canne — the squat bottles sold across the Antilles and increasingly in good bottle shops — is the authentic shortcut and a genuinely good product. But it is ten minutes of work to make a fresher version at home, and the house version lets you choose the sugar, which is the whole game.
The Build
Choose the Sugar
Use a cane sugar with some of its molasses still in it. Turbinado, demerara, or a light raw cane sugar gives the syrup the warm, grassy depth that defines it; plain white granulated works in a pinch but lands closer to a rich simple syrup. Avoid dark muscovado unless you want the molasses to dominate — in a Ti Punch it should support the rhum, not bury it.
Dissolve, Don't Boil
Two parts sugar to one part water by volume. Warm the water gently and stir the sugar in off a hard boil — a rich 2 : 1 syrup needs a little heat to dissolve fully, but boiling drives off water and pushes the ratio thicker and unpredictably sweet. A cold-process version works too: combine and shake or stir in a sealed jar over a few minutes until clear. Either way, stop the moment the syrup runs clear.
Storage and Shelf Life
The high sugar concentration is a preservative — the same logic as a cordial or jam — so a 2 : 1 cane syrup keeps about a month refrigerated in a clean jar, longer than a 1 : 1 simple. Discard at the first sign of cloudiness or a fermented smell.
Bottom Line
If you make Ti Punch, Daiquiris, or anything built on rhum agricole, keep a jar of cane syrup in the fridge and reach for it instead of simple. The molasses thread it carries is small, but it is the difference between a rum drink that tastes generic and one that tastes like where the rum came from.