Keto Simple Syrup

If you mix cocktails or are interested in mixology AND you want to make them low-carb or keto friendly, you’ll quickly run into a brick wall with cocktails that require simple syrup. Since it’s essentially liquid sugar, it’s an absolute ban on any sort of low-carb diet. But fear not, cocktails don’t need to be a bore on a low-carb/Keto diet – we just have to use some science to make some simple syrup. It’s much easier than you think and a fantastic substitute!

The Problem with Not Using Sugar

Real Simple Syrup is incredibly easy to make – just sugar and water. However, the sugar imparts more than just sweetness to the water – It actually adds a certain mouthfeel, which is something cocktail makers want! It’s the je ne sais quoi that you get when you have an egg-less whiskey sour, a gimlet, or a sweet old fashioned. Problem is, low-carb sweeteners don’t add the same mouthfeel. That’s why we need to add a touch of xanthan gum.

Why use xanthan gum?

Xanthan gum gives the syrup the right amount of the ‘syrup’ viscosity that you get from real simple syrup. Just be careful not to go overboard and add more than what’s in the recipe – xanthan gum can quickly turn your syrup into pudding. I’ve found that making a larger batch of syrup makes it easier to measure the xanthan gum as a whole measurement measuring spoon can be used as opposed to a partial measuring spoon – but then you have a ton of simple syrup!

At this point you’re wondering if we really need to add xanthan gum. The answer is no – and I often don’t to my Allulose version. Does it impact a fancy hipster cocktail I might be making? Yes – but the style of cocktails I enjoy consuming, the mouthfeel is not an important aspect (I’m a big fan of margaritas on the rocks). I’ve found that for built cocktails it doesn’t have a large impact. However, for shaken cocktails, it can make a large difference as those varieties focus heavily on the way it feels on the palette (thus the shaking for airation, foam, etc).

Why the different sweeteners?

This is where we get into the science of the Keto Simply Syrup – it’s about to get technical! BUT, there’s a reason there are two versions…

The erythitrol version of the keto simple syrup exists because erythitrol is the most common low-carb sweetener around (e.g. Swerve, Lokanto, etc). Except, erythitrol is problematic because

  1. It’s about 70% as sweet as sugar
  2. It has a dilution rate of 0.49 at standard temperature (70 degrees F), meaning that in 100 ml of water, only 49g of erythitrol will fully dissolve.

So why are these two points issues? The dilution rate means that you’re going to end up with crystals, potentially EVEN if you have the measurements correct. Unless you’re drinking your cocktail at room temperature, you’re most likely going to add ice, which descreases the dilution rate. Thus, you could end up with crunchy little pieces of erythitrol. Keep in mind that in a cocktail, you will also have dilution of the ice, which increases the amount of water in the cocktail, thus allowing the erythitrol to dissolve into that additional water – therefore somewhat equalizing it out.

The second issue is the sweetness ratio of erythitrol to sugar. With the poor dilution rate of erythitrol, that means that with a perceived sweetness of 70%, we will only ever have a keto simple syrup that’s 70% as sweet as regular simple syrup. If we want to increase the sweetness, we would have to add more erythitrol simple syrup, thus increasing the overall quantity in the cocktail and diluting the other ingredients. In other words, it all gets FUBAR. To fix this, we need to add a liquid sweetener – i.e. liquid stevia. Since the stevia is in a liquid form, we don’t have to worry about it dissolving into the water – therefore increasing the overall sweetness of the syrup with just a few drops!

Keto Simple Syrup - Erythitrol Version - Black Tie Kitchen

Keto Simple Syrup (Erythitrol Version)

Yield: 8 oz Syrup
Prep Time: 10 minutes
Total Time: 10 minutes

Erythitrol is a very common sweetener that's relativelty easy to make into Simple Syrup!


  • ½ cup (100g) Erythitrol
  • 1 cup (214ml) water, distilled works best
  • 8 drops liquid Stevia Extract
  • 1/16 tsp xanthan gum


    1. To speed up the process, heat a bit more than 1 cup of water.
    2. In a bottle, add the Erythitrol and xanthan gum.
    3. Add the hot water and mix vigorously.
    4. Add 8 drops of liquid Stevia for each cup of water.


If you see crystals form, it's not a big deal. If you want to get rid of them, simply keep adding little amounts of water until they dissolve!

Nutrition Information
Yield 4-8 Serving Size 1 oz
Amount Per Serving Calories 0Carbohydrates 0gFiber 0gSugar 0g

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Keto Simple Syrup - Allulose Version - Black Tie Kitchen

Keto Simple Syrup (Allulose Version)

Prep Time: 5 minutes
Total Time: 5 minutes


  • 1 cup Allulose
  • 1 cup water
  • 1/16 tsp xanthan gum


    1. To speed up the process, heat a bit more than 1 cup of water.
    2. In a bottle, add the Allulose and xanthan gum.
    3. Add the hot water and mix.


You can skip the xanthan gum if you find it's too much trouble.

Nutrition Information
Serving Size 1 oz
Amount Per Serving Calories 0Total Fat 0gCarbohydrates 0gFiber 0gSugar 0gProtein 0g

Did you make this recipe?

Share it on Instagram! Tag @blacktiekitchen so I can see!

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Keto Simple Syrup - Allulose Version - Black Tie Kitchen

This Post Has 6 Comments

  1. Nicole

    If you make extra, how should this be stored? Room temperature, refrigerator?

    1. Dennis

      In my experience, the allulose syrup can stay on the counter but the erythitrol syrup can develop mold after some time. If you don’t plan on using either within a few days, I’d throw them in the fridge – after all, most cocktails that require simple syrup are served chilled, so it can only help! Just be aware that the erythitrol version will crystallize a bit as the temperature of the syrup drops!

  2. Jenny

    I’ve just started working with Allulose a bit. But Allulose is also only 70% as sweet as sugar, right? So would using more to compensation be ok with how Allulose dissolves? Thanks.

    1. Dennis

      That’s correct! However, I find that the 70% works well as most recipes with real sugar are overly sweet. I’d recommend trying it first to see what you think. If you believe it is lacking sweetness, you can add a bit more allulose or a few drops of stevia to bring it up to ~100%

  3. Lori

    I would be curious what you thought of the Bocha Sweet version of simple syrup. I have made a batch for a whiskey sour and thought it turned out quite nice. I don’t have the chemistry down as you do and would love to see your take.

    1. Dennis

      That’s a great idea! I havent played much with bocha sweet as it is so dang expensive – but simple syrup is… well… simple =)

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