Darcy S. ONeil
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Grapefruit Syrup & Soda
🕑 Added 2025-08-11 19:09:07 +0000 UTCGrapefruit soda is one of the most requested topics I've had, and this method is slightly different from the traditional methods out there, but the results are really good. This formula has a stronger flavour than most commercial versions, mostly thanks to the grapefruit mercaptan, and if you find anything too strong (flavour, acidity, etc.), you can easily cut the amounts back. As usual here, these recipes are a guide for you to make the perfect beverage for your personal tastes, and the recipes are just a starting point to save you time. I dump a lot of syrup down the drain so you don't have to.
Grapefruit Syrup Formula
900 mL Base Syrup
11.0 g Grapefruit Oil Emulsion
1-3 drops Grapefruit Mercaptan Dilution
0.1 g Nootkatone
3 drops Ethyl Butyrate
1 drop Guavante (optional)
40 g Citric Acid
Water, to make 1000 mL
Base Syrup
625 grams Sugar
Water to make 900 mL
This is a 1:1 ratio, and I recommend leaving about 100 mL of space because we will be adding other ingredients to this. Once everything is added, you can top it off with water to the 1000 mL mark.
Grapefruit Emulsion
The emulsion is made using the same technique used in the Crystal Clear Soda Science video, except this one is more concentrated, so you end up using less emulsifier and the foaming and taste issues are much better.
4.0 g Polysorbate 60
0.4 g Span 40 (optional)*
4.0 g Grapefruit Oil
7.2 g Water
~37 g Propylene Glycol
Create the emulsion using the technique in this video.
*Span 40 can be used as a co-emulsifier to improve the stability of the emulsion. It is discussed in the Pepsi patent. Span 40 has a lower HLB value, meaning it is more soluble in oil, so it is mixed with the essential oil first, then added to the emulsifier.
Grapefruit Mercaptan
For that true grapefruit flavour, grapefruit mercaptan (GM) is key. As noted in the video, the amount used is in parts per trillion, so millionths of a milligram. To measure these amounts, use dilutions, and here is the calculation for the sample I bought at Perfumer's Apprentice, which comes in a 1% solution.
1. A 15 mL bottle weighs about 12 grams, meaning a 1% solution has 120 mg of GM
2. If you take 1.0 grams, which equals 10 mg of GM and dilute it to 250 grams using a solvent (alcohol, limonene or triethyl citrate) then 1 gram of the diluted mixture will have 0.04 mg of GM.
3. A typical drop, if you use alcohol as the solvent, is about 25 mg, which means there are 40 drops per gram. This means one drop will have 0.001 mg of GM
4. Since our syrup makes 8L of finished beverage, a single drop works out to 0.000125 mg of GM in a litre (0.000125 ppm or 125 parts per trillion (ppt)). The math is 0.001 mg divided by 8L.
5. The EU usage limit is 0.001 mg (1 part per billion or 1000 ppt), and FEMA gives an average usage of 0.000150 (150 ppt).
In our case, 1 drop is probably sufficient, but 3 drops will give a little extra punch and still only be half of the EU limit. If you want to use less, or have more precise control of your drops, you can simply dilute the 1.0 grams of GM to 500 grams and then everything will be half the amount per drop. For even more precision, dilute 1.0 grams to a litre and every drop with be 1/4 the amount, so a single drop added to 1L of syrup will result in roughly 30 ppt of GM when the syrup is turned into 8L of soda. This is also effective if you feel that the source material may be at a 2% concentration instead of 1%, but at these tiny levels, it can be hard to get exact dosing. Luckily, using this method, the flavour is never overpowering.
Other Flavour Compounds
Grapefruit is a relatively simple flavour once the essential oil and grapefruit mercaptan are combined. Beyond that, there are other flavours you can add to improve the flavour.
Nootkatone: This is a compound found in the peel of grapefruit and has a characteristic grapefruit aroma, making it a great addition. Use at 0.1 grams per 8L. (Source)
Ethyl Butyrate: To give a fruitiness to the flavour, the addition of esters is common. They are used at low levels and help enhance the fruit flavour. You can add many different esters, and typical usage is a few drops per litre of syrup.
Guavanate: This is a compound that resembles guava, but it finds use in grapefruit flavours and can help give depth to your grapefruit flavour. Use a single drop per litre.
Octanal and Decanal: Grapefruit are closely related to sweet oranges; in fact, the parents of the grapefruit are a sweet orange crossed with a pomelo. If you look at the GC/MS analysis of grapefruit oil, you will see the aldehydes octanal and decanal at about 0.5% in the oil. These can be used in a drop or two per litre of syrup to enhance the citrus flavour.
Naringin: This is a bitter compound found in the peel of grapefruits and can help round at the flavour, especially if you appreciate the bitterness of grapefruit. Can be used up to 300 ppm in a beverage, which would be 2.4 grams added to the syrup. This is a bit high and I've found 0.5 grams added to the syrup to impart a decent flavour. Feel free to experiment, but do note that the naringin dissolves slowly and may cause some haze in the final beverage.
Acidity
Grapefruits are quite acidic, and the juice is up to 2% acid, mostly citric acid. This can make them unpleasant to drink, so for most grapefruit beverages, the acidity is reduced significantly. In this formula, it has been reduced to 0.5% which still creates a tangy beverage and may still be too acidic for some people, but if you like a Daiquiri made with freshly squeezed lime juice, you will like this acid level.
40 g Citric Acid to 1L of syrup
You can also add malic acid or any acid. And you can also temper the acidity using some sodium citrate, which will increase the pH, giving the beverage a less puckery flavour.
Zero Calorie Version?
Yes, you can substitute the Zero Calorie Syrup formula for the syrup in this formula. Do note that you may want to reduce the amount of acid as high intensity sweeteners work slightly differently than sugar when mixed with high a proportion of acid.
As usual, if you have any questions, please post them below.
Comments
Jeremy
I was finally able to make this grapefruit soda a couple days ago and overall I am really pleased! I do have a few observations from my experience that I think are worth sharing... - The nootkatone I ordered from Perfumer's Apprentice was definitely not in a powdered form like Darcy mentioned his was in the video. Maybe he got his from a different source? Mine arrived in liquid form and slowly solidified as it cooled down in room temp storage. To use it in the formula, I submerged the vial in warm water and added it in drops. -Darcy isn't kidding about the potency of the grapefruit mercaptan. Holy smokes. I used two drops of the dilution and I think I'm gonna pull it back to one drop next time around. Darcy comments that they add "punch", but I would describe it as "funk" (not in a bad way, per se!). It definitely adds a level of realness/authenticity to the flavor. It was very perceptible in the first soda I made right after making the syrup and made me worried I had overdone it. It mellowed out in the day or two after. However, I personally think I want to make it a bit more subtle in future versions. I still want it though. - Darcy also wasn't kidding about the naringin being slow to dissolve. Even after 30 mins of vigorous stirring on my stir plate's fastest speed, there were still clumps of the stuff swirling around. I had to break out the big guns and use a stick blender to get things homogeneous. That worked for the clumps, but the fine particles still seemed to swirl in suspension on the stir plate like it was a snow globe. After decanting the syrup to a serving bottle, some particulate did settle to the bottom after refrigeration. I used the 0.5g recommendation. I wonder if that's too much or if I need to heat things up a bit next time. I do like the bitterness, so I'll keep using it in future versions. - I am happy with all of the other recommended flavor adjustments Darcy suggested. The guavanate, decanal, and octanal definitely help make a more complex, pleasing flavor. I am curious if using white grapefruit oil instead of the pink grapefruit I used would make any difference. I also want to play around with the acids more. I used mostly citric (as directed) with a little ascorbic (a last minute call I made). I'm definitely gonna try adding small portions of malic and tartaric to maybe match the organic acid profile ratios of actual grapefruits to see if there is any perceptible difference. I am super happy with this formulation and I look forward to making more in the future!
Jeremy
Someone asked the exact same question in the comments on "The Science Behind Crystal Pepsi" video on YouTube. Darcy's answer was: "The initial water load helps form the emulsion through the interaction of the emulsifier and propylene glycol. It is complex, but once the emulsion is formed it becomes stable in beverages with high water content. Emulsion and colloid science is complex."
Brian Drell
How does the micro-emulsion not break when you add it to the simple syrup? When you’re making the emulsion, an extra drop of water will make it cloudy again. I just don’t really understand how that doesn’t happen when it gets added to a large volume of water.
Darran Ridley
The only really successful way to do any bottling or canning with sodas is with counter-pressure filling. Something like this applies to cans. https://www.northernbrewer.com/products/tapcooler-canning-station
Natasha D
Hi Darcy! I hope you had excellent holidays. What kind of dispensing/filling tool would you recommend for filling aluminum cans with soda from a corny keg? We tried using a growler gun at 30 psi from a cold keg, but it was creating a ton of foam and we were losing almost all carbonation and product. Thanks in advance!
Patrick Jaszewski
The nootketone at Perfumer's Apprentice pricey in the crystalline form and seems like it would be way more than a lifetime supply. Are there other good suppliers or other uses? Alternatively, they have the 10% concentration in TEC for a lower price and could use 10x, I assume
Darcy S. O'Neil
Not everything gets a formula sheet until I've fully worked out the formula and taken feedback, so possibly in the future.
Ramma
A formula sheet to be attached will be better
