Gomme sirop or gum syrup

'Gomme sirop' or 'gum syrup' is sugar syrup with the addition of gum arabic, the crystallised sap of the acacia tree, which adds mellowing mouthfeel to benefit many cocktails, especially sours.

When made with cane sugar (not beet sugar) this syrup is the king of sugar syrups, delivering the sweetness of 2:1 sugar syrup but with extra viscosity provided by the addition of gum Arabic - so much extra viscosity that it can add a discernible smoothness to cocktails as diverse as the Daiquiri to the Old-Fashioned.

Most of the companies commercially making this syrup are French so it tends to be called gomme sirop but is simply gum syrup in English. Like many others, I tend to mix the French and English names to use gomme syrup when I refer to it.

Gomme syrup was widely in use in the mid-1800s and E. Ricket and C. Thomas' 1871 Gentleman's Table Guide includes the following recipe:
"Dissolve 1 lb. of the best white gum Arabic in 1½ pints of water, nearly boiling; 3ilbs. Of white sugar or candy; melt and clarify it with half pint of cold water; add the gum solution and boil altogether for two minutes. This gum is for cocktails."

Gum arabic, the essential ingredient to this wonderful syrup, is also known as gum acacia or meska. This fine white power is made from the hardened sap of two species of the acacia tree; Senegalia (Acacia) senegal and Vachellia (Acacia) seyal. Gum Arabic is used in the food industry as a stabilizer and has the E number E414. It is also used in cosmetics, inks and the textile industry and is the glue traditionally used on postage stamps. Artists will be familiar with gum arabic as it is used as a binder for watercolours.

How to make gum syrup

When you come to make gum syrup for the first time you realise why its use has declined. While it takes only a few minutes to make 2:1 sugar syrup just teasing the gum arabic powder into a paste and then a solution takes at least ten minutes. Then you add your sugar and clarify. It's a bit of a faff but worth the effort. [To be honest, I usually decide it's not and use commercially made gomme syrup.]

1. Start by measuring one cup of filtered or mineral water and ¼ cup of gum arabic powder (powdered crystals).
2. Like cornflour or cornstarch, gum arabic forms clumps when it comes into contact with water and is best first mixed with water at room temperature rather than hot water. Tip the gum arabic into a mixing bowl and add a small amount of the water from the mug. Using the back of a spoon mix the gum arabic and water first into a paste, gradually adding the rest of the water, and then into a straw yellow thick solution with a foamy head. This process takes 5 to 10 minutes but feels like an eternity so put the radio or music on before you start.
3. Pour your gum arabic and water solution in a saucepan over very low heat and add one cup of caster (not granulated) sugar. Stir the sugar into the solution until all the sugar has dissolved.
4. Gradually add a second cup of caster sugar into the saucepan stirring as the sugar is added.
5. Heating helps the sugar to dissolve in the water but also has the negative effect of changing the sugar's physical properties. So do not let the water even come close to boiling and only gently heat for as long as it takes to dissolve the sugar. (The temperature should be low enough to be able to comfortably touch the sides of the pan.)
6. Cover and allow syrup to cool. You will end up with a thick straw yellow syrup with a white foamy head. It helps if you cover and leave this to stand for at least 24 hours.
7. Pouring through a fine strainer into a sterile container with a tap near its base and leave for 24 hours to settle and so clarify. Draw of your gomme syrup through the tap to separate from any settled deposits and foamy head.
8. Place in a sealed sterile bottle and place in a refrigerator where your gomme syrup will keep for six months.