Have you ever wondered if you can brew kombucha using a herbal infusion instead of traditional tea?
Maybe you are doing something like a “locavore challenge” and only eating and drinking what can be grown or produced within 100 miles of your home. Maybe you are a prepper of some sort, wanting to know if your kombucha scoby will survive on your local tea substitute plants. Or maybe you like the idea of bitter-herb spring tonics, but find them to be too, well frankly, bitter!
This question about using herbal tea to make kombucha is one of those queries that you’ll see come up time and time again in fermenting forums. It’s a variation of the “do I have to use normal tea?” question, and is usually answered with the traditional wisdom that ordinary black, green or oolong etc tea is what kombucha needs and that to stray from that is to invite disaster.
It appears that, like much of life, the truth is much less straightforward.
It turns out that you can successfully use a kombucha scoby to ferment herbal infusions.
But there are some cautions and provisos to consider:
1. Firstly, and probably most importantly, fermenting the infusions has an entirely unpredictable effect on the therapeutic properties of the infusions. So if you are using a herbal infusion for its specific medicinal properties (e.g. St John’s Wort for depressive symptoms), you absolutely cannot be sure what fermenting that tea will do. It might make it more potent, it might make it less potent, it might even worsen your symptoms. Proceed with caution, if at all.
[Here seems like the right point to state again that I am not in any way a medical or health professional. If you want to explore this further, try and find a naturopath or herbalist who is also an expert fermenter.]
2. On the other hand, if you are using the infusion because of its more general antioxidant, antimicrobial, astringent etc properties (like a general spring tonic), these do seem to be enhanced by fermenting with kombucha – at least in the herbs examined here.
3. Each of the herbal infusions looked at in this study were rich in tannins, nitrogen and phenolic compounds – all compounds that the kombucha scoby needs in order to grow. It’s possible that other herbs with lower levels of these might not work so well.
This month I’m looking at three research papers produced by two different research labs based in Mexico and Serbia.
Antioxidant and antibacterial activity of the beverage obtained by fermentation of sweetened Lemon Balm (Melissa officinalis L.) tea with symbiotic consortium of bacteria and yeasts. Velicanski et al. (2014) Food Technol. Biotechnol. 52 (4) 420-429.
Antioxidant and Angiotensin-Converting Enzyme inhibitory activity of Eucalyptus camaldulensis and Litsea glaucescens infusions fermented with kombucha consortium. Gamboa-Gómez et al. (2016) Food Technol. Biotechnol. 54 (3) 367-374.
Each of these papers began with the observation that when you use a scoby to ferment ordinary tea, that the chemical profile of the tea changes. It enhances the polyphenol and antioxidant profiles of the tea, making it more complex, and it also improves the antibacterial performance of the drink. They also discuss how the fermented tea, the kombucha, has quite a different look and taste to normal tea.
So, the researchers asked themselves what would happen if they chose a different plant-based infusion and fermented that instead.
The herbs chosen were, variously, Lemon Balm, River Red Gum, Mexican Bay Leaf, and White Oak. These are all used in their native parts of the world as both refreshing drinks and also as herbal tonics to treat a variety of conditions. They are all astringent herbs with a range of polyphenols in them, and (generally speaking) a good selection of tannins.
So, What did they find?
Lemon Balm Kombucha, (made from Melissa officinalis L.) showed higher antioxidant activity than both ordinary kombucha and plain lemon balm tea.
These researchers also tested the Lemon Balm kombucha to see how antibacterial it was. Lemon Balm kombucha successfully blocked the growth of all the bacterial strains that they tested, including pathogens like listeria. They concluded that most of this antibacterial activity was due to acetic acid – just like with ordinary kombucha, but they also note that if you take kombucha and neutralise it so that it is not acidic any more, it still has some antibacterial properties, so there are some other compounds in there that are antibacterial as well.
The River Red Gum is a native plant of Australia (Eucalyptus camaldulensis), and is a traditional Aboriginal medicinal herb. When the tea is fermented with a kombucha scoby, the concentration of phenolic compounds is increased. This research group used a number of different tests to measure antioxidant activity. Depending on which test they used, they got quite different results, meaning that only some types of antioxidant activity increased.
River Red Gum can be used as an anti-hypertensive to help control high blood pressure. Fermentation with a scoby decreased its anti-hypertensive properties two-fold.
Mexican Bay Leaf (Litsea glaucescens) is a traditional medicine used by the Tarahumara people of North-east Mexico. It is commonly used to treat headache and gastro-intestinal complaints.
The River Red Gum and Mexican Bay Leaf research was published in the same research paper, and the tests performed were identical for each.
When Mexican Bay Leaf tea is fermented with a kombucha scoby, the concentration of phenolic compounds decreases (the opposite of what happened with River Red Gum).
And, like we saw with the River Red Gum, Antioxidant activity increased with some measures, but was unchanged with others – but not in the same ways. So different types of antioxidant activity improved, and to different degrees.
Mexican Bay Leaf tea has good anti-hypertensive properties (probably why it is good for headaches), but fermentation reduced its effectiveness by fifteen times.
White Oak is a traditional Native American medicinal herb. It is valued for its astringent, antiseptic and anti-inflammatory properties.
This research group (the same group that produced the last paper on Mexican Bay Leaf and River Red Gum) tested three different varieties of White Oak, and performed a whole raft of antioxidant tests. Based on the results, and what we already know about how variable ordinary tea kombucha is, my take-away is that White Oak kombucha is pretty comparable to normal kombucha. It is a good antioxidant, keeps its anti-inflammatory properties, and has some key compounds in it which have been shown to decrease oxidative stress.
As you can see, the results were a bit mixed. In most cases the antioxidant power of the infusion increased after fermentation, but this depended on which test was used to measure that. It wasn’t a definite green light across all measures.
Again, when measuring the total concentration of phenols, in most cases this increased and got more complex – but not with the Mexican Laurel. For some reason the phenolic concentration decreased with that herbal infusion.
And when a particular medical effect was measured, like when the Mexican research group measured the anti-hypertensive properties of Mexican Laurel and River Red Gum, it got even less predictable. Fermented River Red Gum was only half as effective as the plain infusion, and fermented Mexican Laurel was fifteen times less potent than the plain infusion – a situation where fermented tea is definitely not an improvement on the plain tea.
In terms of how the fermented versions of the teas tasted, this was only researched in one of these experiments – the paper which compared Mexian Laurel and River Red Gum. The researchers got a panel to taste-test the results, and the fermented product compared favorably to the original, but people still didn’t really like it as much as ‘real’ kombucha although it was pretty close.
We also know from these Chinese studies that I discussed previously that you can make a mix of known medicinal herbs, combine them with normal tea, and brew kombucha from them, and that this Chinese Herbal Kombucha has got anti-viral properties that has been successfully used in animal husbandry settings.
Which leaves us where, exactly?
Well, it basically means that there is no one size fits all answer. Fermenting a herbal tonic with kombucha will not always improve the drink, and sometimes it will make it worse. All we can say is that it will change it somehow.
But let’s bring this back into context. It’s important to remember that we’re talking about living systems here. The leaves harvested from the River Red Gum in the dry Australian outback will be different to leaves from a River Red Gum in the rainy Pacific North West. Likewise, the potted Lemon Balm plant growing in full sun by your back door will be different to my neighbour’s Lemon Balm grown in well manured soil under the shade of tree. We are talking very high levels of variability already existing in the herbs being used here.
Add the fact that everybody’s scoby is different, and we end up with a highly unpredictable situation in terms of whether fermenting will be medically beneficial. It’s just impossible to say, one way or the other, without specifically testing the specific herb and scoby being used.
In fact, I would go so far as to say that if you are wanting to use herbal infusions for specific medical or health outcomes you should purchase your herbs from a reputable herbalist practitioner, and do so in consultation with them.
But there are other reasons why you might be wanting to give this a go. As I said at the start of this post, maybe you are trying to eat and drink only items that don’t need to be flown across the world? Maybe you want to find out if you can be self-reliant with your own local resources and still make kombucha? Or maybe you just want to try something different.
The key take-away from these papers for me is that the kombucha scoby is highly adaptable. It may not immediately love the new brew, and you might need to gradually start the scoby on a mix of tea and your herb of choice before gently coaxing it to ferment the herbal infusion on its own (with sugar or some other sweetener, of course – don’t leave that bit out), but it will make the switch eventually.
It might not be kombucha as you know it, and it would be prudent to drink small quantities at first to test how your body reacts to it, just as you may have done when you first started drinking normal kombucha, but it may well work brilliantly.
Do your homework, make sure that the herb you are using is actually the herb you think you are using. Make sure it is completely edible and safe. Observe good hygiene practices.
And then go for it. It’s an exciting wide world out there, and you never know what flavor sensation awaits you.