While developing a cocktail recently, I decided I wanted to try gum (or gomme, if you prefer the old-fashioned style) syrup. Even in our nation’s best cocktail bars, it’s still a rarity to find this once-common ingredient. I’ve read many praises of the mouthfeel it imparts to cocktails and wanted to give it a shot myself.
Everyone on the internet describes gum syrup as difficult to make, and blames that for its disappearance, but after a little digging it didn’t seem hard at all for someone who has used hydrocolloids a little. You’ll read a lot about people having clumping problems on the internet, which seems to be because they don’t know how to properly disperse it. I had that problem when I first started working with hydrocolloids too. Had anyone bothered to ask a modernist chef they’d probably have found it was much easier to make than they thought. Luckily I’m a modern cuisine hobbyist, and even though I’m far from a professional I was up to this task.
Gum syrup is really just rich simple syrup with gum arabic mixed in. Gum arabic is a hydrocolloid, which is basically a substance that forms a matrix when dissolved in water. You’re probably familiar with a few other hydrocolloids. Gelatin, pectin, and xanthan gum are all common ones. You’ve probably unknowingly eaten locust bean gum in commercial ice creams, and agar-agar in vegetarian desserts or Asian cuisine.
The first step in using a hydrocolloid is to hydrate it. This means getting it to do it’s magic in water. With some hydrocolloids (like gelatin) this takes heat. According to the Cooking Issues Hydrocolloids Primer, gum arabic hydrates under shear, meaning force is required. This actually makes it easier to work with, as hydrocolloids that require heat can often run into problems like premature gelling. When it comes to shear, your blender becomes your best friend.
So I started looking into recipes. My first thought was to turn to Jerry Thomas’s Bartender’s Guide, but the recipe there is really just 2:1 simple. Maybe gum syrup was largely gone by that point already. In David Wondrich’s Imbibe, (a fantastic book by the way, I just got the newly-revised edition linked here and love it) he quotes the Gentleman’s Table Guide as such:
Dissolve 1 lb. of the best white gum Arabic in 1 ½ pints water, nearly boiling; 3 lb. of white sugar or candy; melt and clarify it with half pint cold water, add the gum solution, and boil all together for two minutes.
The technique here is bad, but the ratio is what I wanted. Unfortunately this uses imperial measurements and switches from weight to volumetric and back and forth again, so I thought I’d modernize it. Luckily for us, a pint of water weighs a pound, so it’s easy. I’ll decrease the recipe, changing a pound (or a pint) to 100 grams and convert to metric and we have:
100 grams gum Arabic
150 grams water, nearly boiling
300 grams sugar
50 grams water
Essentially this is a 3:2 simple syrup with gum Arabic equal to 1/3 of the weight of the sugar. Most of the modern stuff I’ve seen uses a little more sugar (more like 2:1 than 3:2) and a little less gum.
In Jeffrey Morgenthaler’s Bar Book, he instead recommends a 2:1 simple with gum Arabic equal to 1/6th the weight of the sugar. He leaves the gum to soak in water for a couple days to hydrate, but according to the primer it’s shear that hydrates it so I’m not sure why this even works but I’ll take his word for it that it does. Maybe Brownian motion provides enough shear force over two days. He does this because with a blender alone he got the familiar clumping one will experience when adding a hydrocolloid to water, but modernist chefs long ago discovered a cheap, quick and easy way to help mitigate that.
So I came up with my own method for making gum syrup. This makes about 2 cups by volume. You probably don’t want to go below this as I’m not sure you’d get enough of a vortex in your blender to disperse the gum, but you could probably double or triple this with no problems.
100g gum arabic
I decided on a 4:1 scaling of sugar to gum arabic, figuring I’d lose some to the sides of the blender or floating off into my kitchen. It probably comes out a little gummier than Morgenthaler’s.
1. Hydrate the gum Arabic. Pour the water into the blender and run as fast as you can without it flying out of the top. In my Vitamix that’s about level 3.
Disperse the gum Arabic through a sugar/flour shaker into it. Gum arabic hydrates via shear, so most people who have problems are probably trying to whisk by hand, or are just pouring it in. You want each individual grain of the gum to be as far apart as possible from other grains to prevent clumping, and the shaker does this well. Just hold the shaker upside-down above the running blender and tap on it repeatedly until it all comes out. You can do this pretty quickly. Run the blender on high (now that it’s gummy it won’t splash much) for a couple minutes. You’ll see a thick syrup that looks like this:
(I believe you could skip this step entirely by using a pre-hydrated gum Arabic and just dump it into the next step. )
2. Put your sugar in a heavy-bottomed 1 qt. sauce pan. (Use a bigger one if you’re scaling up or you’re going to napalm yourself and burn your house down.) Heat over high heat, stirring and scraping the bottom, until it boils and foams rapidly and looks like this:
(Mine is brown because I used demerara sugar here.)
3. Stir the foam down and then pour into a container to cool.
(These will also be great “before” pictures after I remodel my kitchen.)
4. At the end a layer of scum will form over top. Skim it off, and you’re left with a beautiful gum syrup.
You can tell pretty quickly that this isn’t just simple syrup. For comparison, I made a little 2:1 demerara simple. Here’s a gif showing their viscosities (gum on the left):
As you can see, the gum syrup is cloudier and significantly more viscous than a 2:1 simple.
So there you have it. Fast and easy gum syrup. No waiting two days, no clumping, and no straining.