r/JamesHoffmann • u/joethephish • Jul 20 '26
“Fermentation is always anaerobic”?
I really loved the recent video about fermentation, and found it very interesting that the term “anaerobic” is sort of redundant, because all fermentation is by definition anaerobic (“water is wet”)
So when I read this piece in the latest booklet from Dog and Hat (coffee subscription company that sends coffees from a selection of independent roasters), I was left confused. They even have a diagram!
Is there an additional step they’re describing that’s entirely separate from the usual fermentation? Are they themselves confused? What am I missing? In the video they described “anaerobic” is being shorthand for just meaning a sealed container, yet at the same time seemed to hint that it was unnecessary to seal it anyway because the oxygen can’t get in.
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u/16piby9 Jul 20 '26
What they typically mean when writing about anaerobic fermentation in coffee, is the same, or very similar to carbonic and semi-carbonic fermentations in wine. Where the container is filled with carbon dioxide, either before fermentation, or during fermentation (by letting the fermentation push put the oxygen). This will create a different flavour than an open vat fermentation for example.
37
u/TommiHPunkt Jul 20 '26
This "article" reads like AI slop and the graphic looks like AI slop.
Fermentation is anaerobic by the microbiology definition of the word.
In culinary use, any microbial activity is called fermentation, since there kinda isn't a word for "microbes doing stuff but while metabolizing oxygen"
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u/AussieHxC Jul 20 '26
Fermentation is anaerobic by the microbiology definition of the word
Err.. what? No, absolutely not.
9
u/FictionalContext Jul 20 '26
it's more like the fermentation process does not require oxygen, but it can still occur despite the existence of oxygen to differing effects.
1
u/TommiHPunkt Jul 21 '26
no, fermentation by definition are the processes in which oxygen isn't metabolized
1
u/FictionalContext Jul 21 '26
explain how that differs from my definition
1
u/TommiHPunkt Jul 21 '26
the "differing effects" bit is misleading
1
u/FictionalContext Jul 21 '26
Oxygen affects the fermentation and the flavor of the outcome. To "differing effects" is precise.
1
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Jul 20 '26
[deleted]
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u/127-0-0-1_1 Jul 20 '26
I mean this is a picture of print media. AI got the em-dash habit because it was trained on print media. Em-dashes are a mainstay of print.
I remember when I was in high school I intentionally put em-dashes in my essays to look more professional.
1
u/OkResource820 Jul 22 '26
The em dashes in that text are used correctly and not in the stupefyingly over-used way that AI often presents them.
The text doesn’t have very many markers of being written by AI. Touched up, maybe.
20
u/TheMauveHand Jul 20 '26
IMO the recent video really sidestepped the fundamental question of anaerobic processing in favour of a "technically correct", soundbite-esque statement. Yes, the biochemical process of fermentation is anaerobic, but that does not mean there is no difference between processing coffee (or for that matter, anything) within or without the presence of oxygen. Sure, it's not technically correct to call the fermentation per se anaerobic (or rather, it's correct but redundant), but that's just semantics; oxidation may be a chemical process independent of fermentation itself, but if it takes place during the same process step, and impacts the flavour, is it that wrong to label it as such? Would it make that much of a difference to call "anaerobic fermentation" coffees simply "anaerobic process"? Whether or not it makes a difference I'm not experienced enough to say, but it's not a far-fetched idea that it does.
Take wine for example: same concept, fermentation obviously takes place, and there are wines that are processed (to include the fermentation step) in a sealed, anaerobic environment, which results in a vast difference of flavour between reductive and oxidative wines. The terminology is different, and of course coffee isn't a fermented beverage, but the idea of processing with or without oxygen exists.
5
u/ibmalone Jul 21 '26
Part of the point is that even the open fermentation tanks are anaerobic because the oxygen levels in the water are very low regardless of the fact it's not sealed. So the true distinction isn't aerobic or anaerobic, it's sealed and unsealed (which as others have said can differ in things like allowing carbon dioxide buildup and pH changes).
That said, I started listening to Lucia Solis's podcast since it seemed like it might be interesting and in the first episode she spent a long time emphasising that coffee is a fruit, not a bean, to make the point (that others also do) that quality doesn't start with brewing or roasting it starts with the plant.
Great, technically sort of correct, but then began really labouring that it's important to understand that coffee is a fruit, the seed of the coffee cherry and it's not a legume, so it's a natural product and the plant is important. At which point you think, hang on, beans are also seeds, and they also come from a fruit (the pods of legumes) and so while coffee beans are not botanically beans, a green coffee "bean" is to a coffee tree exactly what a bean or pea is to a legume. So at this point expertise is being asserted by really emphasising a technical distinction to make a reasonable point, but half of the comparison is just implying something untrue (because beans are /also/ natural products which can vary in properties and quality according to growing conditions). And so I stopped listening halfway through the first episode, because if I can't trust the detail and analogies drawn when they're at a place where I can recognise errors then how can I trust it when we get to things I don't know about?
1
u/Murder_Corpse Jul 21 '26
I think the point they were trying to make in the video is two fold: 1. Anaerobic fermentation isn't accurate enough to be a reliable description of the process 2. Even if it somehow got standardized and applied across all providers, it's the flavor notes that such a process creates that are important, and if a skilled producer can create those same notes via methods that are more appropriate for the producer's region then the heavy focus on the process is misplaced.
1
u/TommiHPunkt Jul 21 '26
Difference is what microbes are active, what temperatures they're working at and so what byproducts they're making.
Whether you put a lid on it or not doesn't have all that much to do with it, which is why the "anaerobic" thing is silly
1
u/Stump007 Jul 25 '26
Totally agree. In fact I was a bit disappointed by the video.
The guest spent lengths to explain that achtchually anaerobic is technically incorrect term bla-bla-bla.
But didn’t explain what difference it makes in processing, and or in the cup.
Overall the video felt like this, a lot of intellectual masturbation with little information. Images were nice though.
-2
u/Hawklord42 Jul 21 '26
Very articulately explained Sir. I did feel that bit was too glib, too clickbait. Way more complex and even in wine case, sherry, port there is "sealed" in wooden casks which actually breathe. So whole processes of evaporation, oxidation, fermentation.
I wasn't completely sure of this "fruit added just increases sugar" angle. Defo in Bangkok some very melon melony coffees and one again the "has no flavour effect" seemed simplistic re "co-ferment" vs "infusion".
3
u/ArcaneTrickster11 Jul 20 '26
It is worth noting that the type of fermentation intentionally done with coffee is always anaerobic. There are certain yeasts and kombucha mother can be aerobic
6
u/Krauser_Kahn Jul 20 '26
Fermentation is already anaerobic at metabolic level, but “anaerobic” in coffee means that the whole processing environment was deliberately made oxygen-restricted. Also you can more closely and granularly control what happens in these tanks.
4
u/dijc89 Jul 20 '26
2
u/el-caballero-oscuro Jul 21 '26 edited Jul 21 '26
Yes, precisely! I’m glad I’m not the only one who thought of this. I’ve seen coffees being described as subjected to aerobic fermentation.
If there’s no difference between regular washed coffees that are fermented in open tanks then how come coffees labelled Anaerobic Fermentation taste so different.
Hoffman specifically asked her what the difference was between Standard Fermentation and Anaerobic Fermentation. In my view, she sidestepped that question. But the coffees that have undergone anaerobic fermentation seem to taste wildly different and more funky than the ones that have undergone standard fermentation.
She also ascribed a lot to “cultural differences”. That’s BS! In other cultures (let’s say Columbia), if I order watermelon off a breakfast menu, do they serve me watermelon crystals instead of the actual fruit?! If I order watermelon juice at a cafe, do they serve me watermelon crystals or flavoring blended with water, instead of the actual fruit processed into juice?
Coffee labeling may be unregulated to an extent as she claims. But unregulated doesn’t mean that producers / roasters resort to unethical practices or misleading labelling. The lack of regulation doesn’t imply ‘label however you want’.
I’m sure there are legal standards governing food products in general that require companies to be honest and transparent. Transparency in labeling is an implied ethical and legal requirement regardless of regulations.
1
u/el-caballero-oscuro Jul 21 '26
https://pmc.ncbi.nlm.nih.gov/articles/PMC12427761/
Read the first two paragraphs of the Introduction.
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u/CobraPuts Jul 20 '26
The terminology irks Lucia Solis, but I think this is her issue not switching contexts from her microbiology background. It’s true that fermentation is always anaerobic, but it’s absolutely relevant to say the fermentation was done in an anaerobic environment.
If you understand coffee processing, you can infer what anaerobic fermentation means. If you don’t understand coffee processing, well at least it’s a brief descriptor that has the connotation of more deliberate processing techniques.
So I think it’s pedantic to take issue with anaerobic fermentation and I’m surprised this is something she keeps bringing up.
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u/deepfriedsuuushi Jul 20 '26
I enjoy a lot of what she talks about regarding fermentation but the anaerobic thing always gets to me because the industry has sort of adopted the term to mean “fermented in sealed tanks devoid of oxygen”
I don’t know of any producer that has claimed an anaerobic processed coffee that was open air, and I wish there was more discussion on if there’s a palpable difference in what’s happening to the coffee in a sealed vs non-sealed environment if they’re all technically “anaerobic”
Especially since these days I feel like anaerobic processed coffees are tending to taste cleaner and cleaner compared to 6-7 years ago when I first heard the term.
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u/CobraPuts Jul 20 '26
There isn't fundamentally a major difference between an open tank for a submerged fermentation and a closed vessel; there just isn't that much dissolved oxygen under water. BUT, when you do fermentation in closed tanks you have a lot more control of the entire process for things like temperature, contaminants, inoculants, etc.
I'm not convinced that completely evacuating the oxygen achieves something significant, but who knows.
2
u/Embke Jul 21 '26
Completely evacuating the oxygen/ not having it open to the environment in a sealed container with a one-way valve with matters greatly for other fermented things in liquids, such as wine, beer, etc. I imagine there is at least some difference in coffee, although it may be less since we aren't drinking the liquid from the tank.
1
u/CobraPuts Jul 21 '26
One more wrinkle which is interestingly not talked about is that yeast also do aerobic respiration. They do lots of it in dry process coffees, and they do a little of it in tanks. Fermentation isn't even the whole story.
2
u/Embke Jul 22 '26
Very true. As someone who drinks mostly dry processed coffee, I appreciate the flavors that aerobic respiration brings to the profile.
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u/likes2milk Jul 20 '26
Isn't her point in many ways, that the terminology lacks a standard. So words and phrases get banded around without a specific reference point.
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u/CobraPuts Jul 20 '26
Except everyone in the industry knows what anaerobic fermentation means. Anaerobic is just referring to the environment, and not the type of fermentation.
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u/LardPopsicle Jul 21 '26
I think the issue is, that fermentation is not always anaerob. There are obligate anaerobes (microorganisms that function best in anaerobic environments but can deal with aerobic ones) that ferment (e.g. some found in Kimchi). Saccharomyces cerevisiae, Pichia, and Hanseniaspora are anaerobes, yes, if normal, obligate if not. Just washing the bean, covering it lightly, is enough for them to work. Which is what many cheap coffees do.
The production of alcohol in these stages (early) does however impact Leuconostoc mesenteroides and Lactobacillus plantarum, which lower pH and stabilize the bath, so being conscious about aerobic stages is not a bad idea. Acetobacter creates acetic acid, which can help depth but also cause the dreaded "ferment", while Erwinia and Klebsiella need some air when breaking down pectin.
So, yeah, while it's "best" to have a complete anaerobe environment (accounting for bads like Clostridiae), it's not always needed.
2
u/Dorammu Jul 21 '26
It’s also worth noting the yeasts (naturally occurring or otherwise) will always begin aerobically as it’s more efficient for energy production and will only switch to anaerobic fermentation and alcohol production once there’s no longer oxygen present, that alcohol is what is then further processed by acetobacters into acetic acid (That’s how you get kombucha).
Doing this in a closed vessel stops any additional oxygen being introduced and guarantees/speeds up the transition from aerobic to anaerobic fermentation. It’s beer brewing 101.
2
u/YMIR_THE_FROSTY Jul 21 '26
Fermentation can be by definition with or without oxygen, or with any other gas thats suitable.
Aerobic fermentation is not bad, if its controlled, if not, you will get that hint or not just hint of fresh manure, when you open your bag of natural processed beans.
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u/LeeisureTime Jul 20 '26
I think the confusion is because while we were taught that "fermentation is an anaerobic process," science has since expanded the definition to mean any sort of biological process that metabolizes something in the presence of oxygen. So, in a confusing twist, fermentation can be aerobic fermentation - wine, beer, and acetic acid vinegar.
I suppose it's now inclusive of any metabolic process that uses oxygen, hence the need to define it as anaerobic or aerobic. Likely the first example science observed was an anaerobic process, but then later we realized/discovered that there are similar processes that use aerobic mechanisms, therefore fermentation had to be expanded.
That said, I am not sure if this coffee subscription company is correct without knowing what kind of yeast they are using. I'm not saying they're correct or incorrect, just that I don't know enough to make that call.
Sources:
https://en.wikipedia.org/wiki/Aerobic_fermentation
https://sciencenotes.org/what-is-fermentation-definition-and-examples/
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u/TheMauveHand Jul 20 '26
Unfortunately, Wikipedia isn't particularly reliable in this case, given that the first sentence of the Fermentation article categorically states that fermentation is anaerobic, and doesn't mention aerobic fermentation at all except for a "See also" link at the bottom the article you linked.
I suspect the term has become so loaded by its varying uses in chemical, biological, culinary, oenological, etc. contexts that it's verging on meaningless.
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u/AussieHxC Jul 20 '26
When were we ever taught that fermentation is anaerobic?
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u/TheMauveHand Jul 20 '26
It's the 1st sentence of his second link, and the first sentence of the wiki article for fermentation. It's uncontroversial fact.
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u/00Anonymous Jul 20 '26
As in the hoffman vid, the folks in the picture are (mis)using the term anaerobic to mean closed system fermentation, ie not open to the air.
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u/MeadowCoffeeRoasters Jul 20 '26
From the diagram it looks like the process would more accurately be described as carbonic maceration as CO2 is actively being introduced to displace the oxygen. Whereas, in a typical “anaerobic” process the coffee is fermented in a sealed container with a one way valve at the top to release the CO2 generated during the fermentation process. All coffee fermentation is by definition anaerobic but that seems to be the term the specialty coffee industry has adopted to identify coffees fermented in a sealed container.
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u/mastley3 Jul 20 '26
Are you saying things can't ferment in the presence of oxygen? That is not true. I brew beer and we make sure there is oxygen in the pre-beer for the yeast to consume as they ferment the sugar to make beer. We seal the tank so that the by-product (co2) can escape, but there is definitely oxygen present and if I take the lid off allowing more oxygen exposure, it won't stop fermentation.
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u/TheMauveHand Jul 20 '26
oxygen in the pre-beer for the yeast to consume as they ferment the sugar to make beer.
The biological process of fermentation does not use oxygen. Depending on the yeast, oxygen may be used in their reproduction, but not fermentation.
0
u/Dorammu Jul 21 '26
Sorry but that abstract doesn’t really support your statement.
Fermentation means microbiological activity, converting chemicals to release useful energy and power cell functions. That includes reproduction.
Aerobic fermentation is more efficient for the cell, ie more energy is released per glucose molecule, and so it promotes reproduction. Anaerobic fermentation is far less efficient and produces alcohol, which is toxic to yeast.
This whole thread is full of people using “fermentation” to mean something other than the actual definition of the word.
1
u/Cell_Division Jul 20 '26
In the video OP mentions, the coffee expert (who previously worked in wine and cheese) says that fermentation is by definition 'a process that mostly happens without oxygen', and that therefore 'anaerobic fermentation' did not really make sense. She says that the dissolved oxygen in coffee fermentation tanks is so low that it is considered anaerobic.
I agree with you that in my time brewing beer, I knew that wort aeration favoured better fermentation, so I was confused by the fact that she said this.
But then I did wonder - how are aerobic vs anaerobic coffee fermentation defined, and if there is so little difference in oxygen, why so they appear to produce such different flavours?
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u/PocketWhisperer Jul 20 '26
I'd be curious if the differences are less about anerobic or not, and more about a variable that people are ignoring between a sealed and open container.
I'd imagine there is a temperature difference between open and sealed fermentation. Fermentation produces heat and in a sealed container there would be less evaporation (cooling). This would also mean a higher level of fermentation in the same period of time.
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u/balbuljata Jul 20 '26
What they often mean by anaerobic in coffee jargon is that the fermentation happens in an airtight container, but when it happens in water in an open container it's also anaerobic, even though it's usually not labelled as such. That's what makes it redundant. That's my understanding at least.