This post was last updated on March 19th, 2018 at 09:48 pm
That’s a question I hear A LOT in kombucha discussions. And until now my answer has been, “Yes. If you possibly can.”
The reason I said that was because kombucha scobys have been raised and cultured on plain white sugar for generations now, and if you want the best kombucha from your scoby, you need to stick to the basics and give it white sugar.
As my Dad always used to say, “If it ain’t broke, don’t fix it.”
At least… that’s what I thought!
Except that today’s studies tell a different story.
But before we get into the main subject of today’s post, I want to quickly address probably the second most common question about sugar and kombucha:
“Do I really have to use that much?”
Understand that the kombucha scoby is using that sugar to survive. The yeasts mostly turn the sugar into alcohol and bubbles, and the bacteria turn the sugar and the alcohol into a variety of acids and other molecules.
Because the yeasts and bacteria are using up that sugar, the kombucha that you drink has a lot less sugar in it than the sweet tea that you start with. (See this discussion about fermentation time and sugar concentration).
Today’s research papers found that, on the whole, the best results were had with about 70grams of sugar per liter of kombucha. (approximately 1/3 cup per quart), although as we know, results will vary from scoby to scoby.
So yes, it might feel like you’re adding a lot of sugar. A cup and a half of sugar looks like a huge amount to add to a gallon of kombucha, but that’s the approximate amount that it needs.
So, with the question of how much sugar dealt with, let’s look at the slightly more complicated question of what type of sugar we should be using.
I used to think that the only real exceptions to the White Sugar Rule were when you have a Jun scoby, which is a specialist cousin of kombucha that lives off green tea and honey, or when you’ve run out of white sugar and you just need to feed your scoby something until you can get to the shop at the weekend.
But the research papers I’m looking at today have given me a whole new understanding of how you can use many different sugars when making kombucha, and why you might want to do that.
So, the quick and dirty summary is this:
- You can actually use any sugar to make kombucha, although which sugar you choose will influence how the kombucha grows, the flavor of the final product, and its lactic acid and alcohol content.
- Sucrose is still the most consistent performer with the best results (shoot for a sucrose concentration of 70g per liter of brew)
- If the sugar you use has a flavor, that will change the flavor of the brew. (e.g. molasses will make it taste a bit like caramel)
- Using a less-refined sugar (such as molasses) adds an extra nitrogen source to the brew, which produces thicker, possibly healthier, scobys, and a more complex nutrient profile.
So, let’s get into it. (If you want to skip to the recipe recommendations and my take on the different sugars to use, scroll down until you hit the “So What?” heading, just below the Curious Snail. Um. You’ll see when you get there.)
The research papers
I’m drawing conclusions from three different research papers for this post. (And also from some of the papers I’ve discussed in the past).
The first one is a paper that I was pining after a few months ago. I thankfully have managed to see a copy of this research article now, and was thrilled to discover that it is not in German after all – only the little bit that I could see online was in German. The rest is in English and made for a fascinating little read.
This research was published in 1993, which makes it possibly the oldest paper that I’ve discussed here so far. Dr. Reiss was following up on some much earlier research from 1922 looking at sugar and kombucha (then known as ‘tea fungus’) and wanted to see if the results were the same using modern laboratory methods (spoiler: they were).
Basically, he took kombucha, grew it using four different types of sugars (sucrose, fructose, lactose, and glucose), and then compared each brew for how much ethanol and lactic acid each one produced. He then gave each brew to a panel of tasters to see how they evaluated them.
He used very refined (laboratory grade) versions of each sugar, so the results from this study are solely about exactly which sugar molecules are available to the kombucha. The results here are not complicated by the extra ingredients that that are a natural part of using less refined sugar sources such as molasses, maple syrup, honey etc.
- The kind and concentration of the sugar produced very little difference in taste.
- Alcohol and lactic acid production, however, are affected:
- Sucrose and fructose produced ‘normal’ levels of alcohol (0.5% – 0.9%), whereas glucose and lactose produced only a tenth of that.
- Sucrose resulted in lactic acid production, but none of the other sugars did (not even lactose! I was surprised.)
The other two studies we’re looking at today are by the same research group that also looked into using kombucha to make yogurt. They’re based in Serbia and are headed up by R. Malbaša. These researchers are conducting all sorts of interesting food technology research with kombucha, and I’m sure we’ll be covering more of their results in the future!
Both of these studies are looking at using sugar-beet molasses as the sugar source for fermenting kombucha, and I’ll consider them together, as the only difference is that in one paper they compared sucrose with molasses, and determined that molasses could give a favorable product. In the next study, they used different amounts of molasses to see if changing the amount of molasses made a difference.
- Brewing with molasses produced kombucha with a more complex array of acids in it.
- The molasses kombucha had a smoother, sweeter taste, despite having less actual sugar in it at this stage.
- Sucrose kombucha produced a relatively high amount of acetic acid (the same acid that is in vinegar), whereas molasses kombucha had a lot less acetic acid and a lot more lactic acid.
- Molasses kombucha used the sugar up at a faster rate than sucrose kombucha did, even though they started with exactly the same amount.
- Molasses kombucha produced a much thicker scoby than the sucrose kombucha in the same amount of time.
So why did they even try this? Why use molasses in the first place?
There are a couple of reasons.
If you are thinking about producing kombucha commercially you might look into using molasses because it is an inexpensive by-product of sugar processing. It’s what’s left once you have refined all the ‘plain white sugar’ out of the sugar beet or sugar cane. It is widely available, and as a bulk ingredient, it is less expensive than white sugar. (Unfortunately, it’s not always cheaper for the average consumer, because we’re not buying it by the ton).
The more compelling reason for us, as home brewers of kombucha, is that molasses contains vitamins, nutrients, and minerals that plain white sugar does not. It’s also used in the industrial production of lactic acid – the very same acid that’s produced by our friendly lactobacillus bacteria.
I was really fascinated to see that when you feed a kombucha scoby on lactose it doesn’t produce a lot of lactic acid, but that it will produce it on sucrose, and will produce much much more lactic acid on molasses.
Lactic acid is a much milder-flavored acid than acetic acid or even malic acid (which you get from fermented apples and the like), so kombucha which is high in lactic acid will still be acidic, and have a lot of acids in it, without necessarily tasting really acidic. (I talk a little bit about the different types of acidity in this blog post here). So this would explain why the molasses kombucha tastes milder and sweeter than the sucrose kombucha – the balance is tipped further towards lactic acid, rather than acetic acid.
Now it pays to note here that Dr. Malbaša’s local sugar refineries are sugar beet refineries. So they were using sugar beet molasses. This product is a bit different to the more familiar sugar cane molasses – it is really bitter, is useless for cooking and baking, and generally considered unfit for human consumption. Think along the lines of blackstrap sugarcane molasses, but even more so.
Don’t worry, though, we can still take their research, make some adjustments, and apply it to sugarcane molasses – which is much easier for us all to find at the supermarket.
Okay, so what does all that mean for us? How does that actually answer our questions, and what does it mean for me if I’m standing in my kitchen with a choice of maple syrup, coconut sugar, or treacle?
I’m so glad you asked that :~)
But before we get into it, a few caveats:
- Remember, YMMV. Your kombucha scoby is different to my kombucha scoby, which is different again to the scobys used by these researchers. Results will vary, the only question is by how much.
- Whenever you experiment with a new kombucha recipe, remember to keep a back-up scoby in the fridge in case it all goes horribly wrong. (I just keep mine in a jar, submerged in kombucha, with the lid on. They keep for months and have always revived just fine for me).
- These research papers only looked at pure, refined sugars and at molasses. What I’m about to do is to GUESS, based on this research, what might happen with some of the common sugars and sugar substitutes that we can access at the store. Please experiment for yourself.
- None of these papers looked at the long-term health of the scoby when grown in these alternate sugars. I can say that a healthy scoby will produce kombucha when placed into a tea sweetened with fructose, for example, but I have no idea at all whether that scoby will still be healthy after multiple generations being grown on fructose. If you really want to use a sugar substitute that has little to no sucrose in it, then be prepared to keep a back-up brew of normal kombucha going so you have a steady supply of healthy scobys to use in your alternate brew.
So, with all those cautions in mind, here are my thoughts on using alternative sugars. I spell out my thinking, and then I’ve got it all summarized in a handy infographic (I know, totally cool, right?) Scroll on down for that piece of awesomeness.
Sugars with a lot of sucrose
Coconut sugar (70% – 80% sucrose)
Maple syrup (60% sucrose)
Rapadura, sucanat, muscavado, panela etc (>85% sucrose)
Molasses (55% – 65% sucrose, depending on which grade molasses you use) If you are in the UK or a Commonwealth country, you may be more familiar with Golden Syrup and Dark Treacle, which are roughly (but not exactly) equivalent to Barbados Molasses and Dark Molasses. Blackstrap Molasses is the same thing in all countries as far as I can tell. The darker the molasses, the less sucrose there is in it, so you may need to use a little more.
Based on the results we just looked at, these sugars should all give a good result using about 1/3 to 1/2 a cup per liter (or quart). Use slightly more for molasses and maple syrup because their water content means you need to add more to get the same amount of sucrose.
In theory, these sugars should perform pretty much the same as white sugar. The research papers that looked at molasses even indicated that the scoby was healthier when grown on unrefined sugar. However, I was chatting with someone on Facebook the other day who said that her kombucha completely failed when she used coconut sugar, so as always, give it a go, but have a back up!
Sugars with low sucrose levels
This is where it gets a bit trickier to guess what will happen. We need to draw on what we know about these sugars, and reason our way through.
Things to know about these sugars:
- Sucrose gets broken down into equal amounts of glucose and fructose.
- Maltose and maltotriose both get broken down into glucose
- According to this research into kombucha vinegar, fructose accumulates in kombucha the longer it grows, so kombucha doesn’t use fructose as much as it uses glucose.
- Fructose is much, much sweeter than glucose or sucrose
Honey (approximately 40% Fructose, 30% glucose, 1% sucrose)
Now we know already that kombucha can successfully adapt to grow on honey because that is what Jun is. I also know that some people have tried to use honey and had complete failures so, as always, YMMV.
People are often a bit nervous about using honey because it is anti-microbial, and they worry that it will ruin their brew. While it is true that kombucha grown on honey is more variable than that grown on sugar, plenty of people report it working well, and it clearly doesn’t kill too many of the good bugs otherwise Jun wouldn’t work.
The sugar composition of honey is not too far away from white sugar, really, since white sugar is sucrose, which digests into 50% glucose and 50% fructose. Honey has a bit more fructose than glucose.
If you really want to use honey to make kombucha, your best bet is to try and get hold of a Jun scoby and use that. A Jun scoby is a kombucha scoby that is specially adapted to grow on green tea and honey, and by all accounts, it tastes divine. (Jun is on my list of things to do this year. I’m keen to try it for myself.)
In the absence of a Jun scoby, you can try to wean your kombucha scoby onto honey. Use half the amount of honey and half a cup of sugar for a few generations before switching to all sugar.
The amount of honey used in a Jun recipe is about 1/2 to 2/3 the amount of sugar used in kombucha. Maybe this is because of the sweetness of the fructose?
My best guess: 2 to 4 tablespoons of honey per liter (quart), depending on your honey
Brown rice syrup (approximately 50% maltotriose, 45% maltose, 3% glucose)
Brown rice syrup is basically 100% glucose because maltotriose and maltose both break down into glucose molecules and nothing else.
In the standard recipe for kombucha, we use about 70g of sucrose, which is the equivalent of about 35g each of fructose and glucose. So (ignoring fructose), 40g of Brown rice syrup will supply about the same amount of glucose as is supplied by 70g of white sugar.
My best guess: 2 to 3 Tablespoons of Brown Rice Syrup per liter (quart), but prepared to increase that if you want extra sweetness because there is no fructose in this brew. It runs the risk of being too tart, depending on which acids are produced.
Agave nectar (approximately 70% fructose, 20% glucose)
To be honest, even though Dr. Reiss’ research showed that kombucha grows okay on fructose, I think this is the sugar substitute that has the least chance of success.
Recall from the vinegar study that kombucha prefers glucose to fructose, and that fructose tastes many times sweeter than glucose. I think the result is likely to be a drink that stays too sweet and doesn’t ferment properly, but give it a go if you’re in an experimental frame of mind!
My best guess: start with 1 tablespoon of Agave nectar per liter (quart) and see what happens!
Okay, so you tried making kombucha with your preferred sugar substitute and it didn’t work.
If you really want to keep persevering, here’s what I would do. Assuming that you have a healthy kombucha scoby that produces good kombucha using the normal recipe, try to wean that scoby through multiple generations onto the sugar that you would prefer to use instead.
Assuming 1-gallon amounts here, start with 1 cup of sugar and 1 to 2 tablespoons of the sugar substitute that you would prefer.
Keep that recipe through multiple generations of scoby, until you have one that is reliably producing good kombucha on the new recipe (discarding each mother scoby as soon as the daughter is a reasonable size).
Then repeat, reducing the amount of sugar and increasing the amount of substitute, by 2 to 4 tablespoons each time until you completely switched over to the sugar substitute.
Alternatively, if the scoby produces a drink that you like with the alternative sugar, but it just doesn’t seem to produce healthy daughters, you can grow your kombucha scoby using the normal white sugar recipe, and use the alternative sugars as a one-off brew. Discard the scoby when it gets tired and grab a fresh one from your normal brew to try again.
Good luck 🙂
Happy brewing, people!