I’ve discussed in my post on how to make sweet hard cider the use of non-fermentable sweeteners like stevia and erythritol. I generally prefer drier hard cider, but I also enjoy balance. That means if a cider has a lot of acid, having a little residual sugar can help balance it. Tannins and their bitter and astringent characteristics are the third balancing element in hard cider. Not having the ability to utilize sugar and sweetness to balance your hard ciders, eliminates an important tool in your cider making toolkit.
There are ways to try to keep some residual sugar by achieving a stuck fermentation or by back sweeting with sugar and treating your cider with sulfites and sorbates or pasteurizing it. Fermentable sugar is the source for sweetness in these processes. The other method is to use non-fermentable sweeteners. Therefore, I wanted to understand how some of these non-fermentable sweeteners impact your cider, specifically organic stevia and organic erythritol.
- What is the impact on specific gravity from adding stevia and erythritol versus sugar?
- What is the sensory comparison of stevia and erythritol to sugar?
To answer these questions, I setup a simple experiment. You can easily duplicate it. Here is the list of what materials I used.
- Accurate Scale – I used one that measures to +/-0.1 grams.
- Four Glass Containers (Aluminum foil can be used for sweeteners).
- Eye Dropper/Pipette
- 3 Spoons
- Paper Towels/Napkins
- 600-800ml Distilled Water
- 10 grams each Sugar, Stevia, and Erythritol
First, I calibrated my refractometer using distilled water. It should measure 1.000.
Next, I added 100 grams of distilled water to three of the glass containers.
Using the small pieces of aluminum foil, I measured out 10 grams of sugar and placed it in one of the glass containers with 100 grams of water. I repeated this for the erythritol and stevia.
I swirled the solution to dissolve The sweeteners instead of stirring to avoid removing some of the water or sweetener. I was careful not to spill any either.
Once the sweeteners were dissolved, I measured the specific gravity using the refractometer. Usually refractometers will measure in Brix or specific gravity. Brix is actually the grams of sucrose dissolved in 100 grams of water. Therefore, this test using 10 grams of sugar should read 10 Brix on a refractometer or 1.040 if it’s a specific gravity scale.
I cleaned and dried the refractometer and repeated this process for the erythritol solution and then the stevia solution.
To ensure I did it right, I repeated this for each solution three times. I averaged these readings and recorded my findings.
The next step was the sensory test. Ideally, I would use a larger panel but my wife and I are the quarantine panel of choice right now. For this part of the test, I simply used a spoon and sampled each solution. We rinsed with water between samples, but I started with the sugar sample since this was the baseline. We noted whether it was sweeter or not as sweet as the sugar and by how much. I recorded our results and averaged the numbers. We tried to ignore any flavors or aftertaste and just focused on the sweetness.
Here is a summary of the results.
|Sweetener||Specific Gravity||Sweetness Perception|
I found is interesting and perplexing that the specific gravity for erythritol and stevia were different from sugar. The specific gravity is supposed to measure density and if I dissolved 10 grams of something into 100 grams of water, I would expect them all be to the same. This led me to do more research on erythritol, where I found out it is endothermic when dissolved in liquid. This means it will have a cooling effect when you dissolve erythritol in liquid. However, it didn’t seem reasonable that I should lose mass. That brought me back to my refractometer. It is setup to measure pure sucrose in water. Erythritol and stevia are not sucrose. Therefore, the index of refraction will not be the same as sucrose. I could test this with a hydrometer but I didn’t want to use that much distilled water and sweetener. That will be another experiment or maybe someone else will explore that and post here.
It is a good reminder that while the tools we use as home hard cider makers are amazing, they only give us good estimates and not absolutes. The 1.034 versus the 1.039, or 5 points is significant if are mixing erythritol and sugar together. Hopefully, you paid attention to how much of each you added and don’t need to use the specific gravity to estimate it afterwards. Its also interesting that the specific gravity doesn’t relate to the perception of sweetness.
The sweetness perception is just our perception. However, the direction is definitely real for most people. Equal amounts of Erythritol will not be as sweet as sugar to most people. Stevia will be significantly sweeter. I have read erythritol is around 70% of the sweetness of sugar. I think it might be as low as 50% and my wife was closer to 70%. My wife doesn’t like the aftertaste of stevia so she had to try the sample a couple times so she could not focus on that taste and just the sweetness. Our perception is that it is 4-5 times as sweet as sugar.
The outcome of all this is that you might read a lower specific gravity when using sweeteners that aren’t sugar and if you are trying to duplicate the sweetness level of sugar in your cider, you need to adapt your amount by the perception of sweetness. If you are using erythritol, that means you will need to add more, which will increase your specific gravity. With stevia, you should use considerably less, which will also impact your specific gravity. Also remember that specific gravity estimates sugar but it is an estimate. There can be other solids dissolved in your cider that impact it. As I have learned, the chemistry is quite extensive and interesting as you explore it.
I hope you will join me in exploring the world of hard cider. Who knows where it will take us.
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