The Future of Coffee

GURU MADHAVAN

The ancient Ethiopian highlands. As the myth goes, a curious goat herder named Kaldi first noticed something odd - his flock dancing with wild energy. The source of their joy?

Dark red berries from an unassuming shrub. A chance discovery that would reshape human history.

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From these humble beginnings in the hills of East Africa, to the gleaming steel machines that now grace our countertops, coffee has fuelled not just beverages, but entire civilizations.

[coffee steamer makes frothing sounds]

It transformed sleepy ports into bustling centres of commerce. Sparked intellectual revolutions in the coffee houses of Europe, and today, orchestrates the morning rituals of billions. Coffee isn't just a drink, it's humanity's most beloved psychoactive companion, a global economic force, and a fascinating interplay of material balances, chemical kinetics, mass transfer, fluid mechanics, and colloidal phenomena, unfolding in each sip.

[the sound of sipping and swallowing coffee]

TONYA KUHL

“I always say I drink it black, like my soul”

JONATHAN MORRIS

“I bought a new automatic pour-over brewer. The first parameter that I just set the metres above sea level”

GURU MADHAVAN

I am Guru Madhavan. And in this episode of Create the Future, my guests are chemical engineer, Tonya Kuhl

TONYA KUHL

Hello, Guru!

GURU MADHAVAN

And cultural historian, Jonathan Morris.

JONATHAN MORRIS

Hi, Guru!

GURU MADHAVAN

We will explore coffee's journey from a shepherd's tale into one of our most enduring traditions and where engineering comes in our pursuit of the perfect cup. So, let’s get started. You're both deep in the coffee world. I'd love to hear about your most memorable cup, the one that really stays with you. Let's start with you, Tonya.

TONYA KUHL

Okay. So Guru, my favourite cup of coffee ever had was about five or six years ago, and it was a Guatemalan geisha. Geisha is a variety that came out of Ethiopia and they started planting it in different locations, and frequently this varietal wins competitions for the best cupping coffee. And as all of these high-end specialty coffees, people are always tasting them black. And in fact, they wouldn't hold up to things like milk and sugar. It's a very delicate tasting coffee, and you pay a premium for this, but it's worth it.

GURU MADHAVAN

Jonathan.

JONATHAN MORRIS

Well, it's a long story, but it's that it's not my coffee, it's the coffee I bought and served to my dad. My dad is a tea drinker. Tea and, uh, if he has coffee - it's throw in a lot of sugar, throw in a lot of milk. I had actually a Panama geisha. I just said to him - “I just want you to sip this black before you put in milk and sugar, okay Dad? Just sip it.” And we were outside at a picnic and, the next time I looked he'd drunk the entire cup. And I said, “Dad, you just drank an entire cup of coffee without sugar, without milk!” He goes, “did I?” And that's because it was a beautiful sweet coffee. So actually that's my favourite cup of coffee, the one that impressed me the most.

GURU MADHAVAN

All right. Tanya, you approach coffee through an engineering lens. So what makes this drink? I mean, something most of us think of as just beans and water. Such an incredibly complex substance.

TONYA KUHL

Oh, I love your introduction that it's just beans and water. And literally, you're 100 percent right. All of the brewing mechanisms that we have are really designed around extracting coffee stuff into water. And there's many, many ways to do that. What makes it so complicated is that just like wine, it depends on the terroir, so the environmental conditions of which it's growing. Just like different wine grapes, there are different varietals of coffee, and they taste different. And then just like with wine, there's fermentation and the yeasts that are used. There's also processing of the coffee cherries - that's the seeds that we take out of the fruit - become our coffee beans after roasting. And so each step along the way, you can impact what you taste. And so it becomes so complicated, you know, growing conditions vary, the varietals vary and how to optimize and maintain the highest quality throughout all of these steps is really a challenge. But people have been drinking coffee for, you know, 800 years or so, and they've gotten pretty good at delivering delicious coffee to us.

GURU MADHAVAN

Jonathan, coffee's been with us for centuries. Tell us how our relationship with it has evolved.

JONATHAN MORRIS

That's a big question, Guru, but let's, let's say quickly! I mean, coffee, we know that coffee grows, native, as it were, wild in southwest Ethiopia is probably where it originated. The variety we normally use, Arabica. But the first records we really have of coffee, date to around the 1450s, 1470s, and that's when coffee in some form began to be shipped from East Africa over into Yemen and we believe it was being used by the Yemeni Sufis first of all, in their religious rituals, but very quickly it became a social drink because basically coffee was not intoxicating.

And so it was a drink that Muslims could drink in public. That created a whole kind of coffeehouse culture in the Red Sea diaspora, the Indian Ocean, all those populations there.

It's not until about the 1650’s that coffee then gets to Europe, where it first takes hold as what we could call, you know, a kind of “exotic”, “good”, later colonial “good” as the Europeans begin to plant it in their own colonies. Where we see a big engineering transformation is in the next stage where we see coffee become an industrial product.

So coffee becomes something that we actually have businesses set up to specifically deal in, to roast in, to create coffees that then go shipped out to the coffee industry. That really starts in the relationship between Brazil and America in the second half of the 19th century. Then in the middle of the 20th century, really, we see coffee becoming more of a kind of a global commodity drunk in North America and Europe on a kind of a daily basis, beginning to penetrate into other markets in the world, such as, Japan and Asia. Finally, we've had this sort of, more recent thing in the 21st century, where coffee is kind of moved from being that everyday accompaniment to being something that once again has a premium around it, a kind of distinguished beverage in the way that we now sort of think of other beverages in the same way.

GURU MADHAVAN

Tonya, you're at the UC Davis Coffee Center in California, and I know sustainability is a huge focus for your team. What are your challenges and what innovations are giving you hope?

TONYA KUHL K

So the challenges, maybe people don't realize this, but I'll, I'll give an example because we're working with universities in Indonesia right now. So in Indonesia, it's the fourth largest producer of coffee. 96% of the coffee grown in Indonesia is by small holder farmers. If you think about how many small holder farmers are actually producing coffee that we consume, it becomes really, really difficult to roll through really involved and appropriate sustainability aspects.

You can't go and inspect all of these different small, you know, a couple of hectare acres or less sort of production.

So you end up with a lot of waste streams. So, you know, the seeds that you're taking out, it's, you know, about 50 or 60% of the mass is waste. You can't feed it to livestock. And so a lot of this ends up being put into streams, because they're using streams to do some of their washing processes. So, you know, these sustainability aspects are really challenging and they directly impact a lot of people's livelihoods and quality of life for the people who are producing coffee.

Guru, let me add something, when you asked about sustainability, I was thinking about the process, but there’s a huge aspect of sustainability with climate change right now. So there's estimates that, you know, 50% of the coffee growing regions will not be able to be used for Arabica coffee in particular by 2050. Arabica is a very delicate plant. It is not very genetically diverse. And so you have a plant that can't tolerate freezing and it doesn't like to get too warm. So you have this narrow band where this plant is happy and that is a large factor of why coffee is grown in these tropical locales, but at high elevations. Most of the coffee growing regions and countries that produce coffee are looking at are there varietals that will - produce well, a good cupping quality (so a high quality taste that can tolerate these increases in temperature). There's also all of the impact of variable rainfall, which is another factor. The flowering is initiated by a heavy rainfall, and then it takes nine to eleven months for the fruit mature and develop, but you have another heavy rainfall, you get another flowering. Most speciality coffee is hand picked, and so you have to repeatedly go back and pick. So if you think about how much labor goes into producing high-end quality coffee, you know, it's 3,500 hand picked seeds that are in a pound of coffee. It's just amazing how inexpensive this delicious beverage is and frankly, it's under threat from climate change.

GURU MADHAVAN

Jonathan, if we look at the technological history of coffee - and you have written extensively about it - should we be thinking about some ethical dimensions around the technology here?

JONATHAN MORRIS

Sure, I mean, I think we came into this period around the turn of the century where we had a massive coffee crisis. We had a huge fall in coffee prices. There were various reasons around that, but in effect, the most pressing reasons were that we had too much coffee chasing too few buyers, equally we had the growth in the provision of robusta coffee by Vietnam. So Vietnam was not a coffee growing country for most of its history, or it grew tiny amounts of coffee.

So in 1988, it was still the 22nd largest coffee producer in the world, which is not a very large producer. By 1998, it was the second largest coffee producer in the world. And the reason that that happened were two reasons. One is that it was growing what's called Robusta coffee. So this is the commodities style coffee, which is a little hardier than Arabica coffee. And the other is that there used to be a kind of an international coffee agreement that used to regulate through quotas how much each producing country produced, a little like OPEC with oil, and that way they managed to maintain the price. That fell apart in the late 80’s, and, as a result of that, we had this glut of coffee. It enabled coffee producers such as Vietnam to enter the market and put a lot more onto the market. And it led to devastation in terms of the price, but that devastation has a very human cost. And that human cost was seen in the number of people who basically pulled out of coffee. It was seen in, in large numbers of people in, Central and South America, stopping growing coffee and becoming migrants bluntly. It generated a response whereby people believed that there should be a more ethical approach to the purchase of coffee. And that was seen first, most strongly in that fair trade movement, which was born in the 80’s, but really came into prominence around the 2000’s. Which is really about putting in a safety net price, saying, well, “we will buy your coffee for a guaranteed price of X. If the market price goes higher, you can go and sell it on the market, or you can sell it to us at the market price. But we guarantee we will pay you this basic price for your coffee”.

So that gave some form of security to coffee growers. The other thing that sort of came in was of course obviously the fear about all the environmental damage that could potentially be done by coffee. Coffee growing expanded massively, really from sort of the 70’s and 80’s in South America because of the adoption of, if you like, new, what they would call ‘technified’ coffee.

Planting coffee, giving a lot of fertilizer, removing all these sort of cover plants and so forth so you could just put the coffee out in rows and rows in the sun. That had devastating effects both on, the environment, on particularly the bird life, on the organic life, and indeed arguably on the coffee because the coffee tended to mature somewhat quicker.

So the other sort of firms of certification that grew up around that were the ones targeting the environment and sustainability. One of those was, the Rainforest Alliance, which kind of does what you might think - it was obviously trying to prevent damage to the rainforest. There's also something like bird friendly coffee, which was introduced by the Smithsonian Institute, which was about, in effect, making sure that there was cover, make it promoting shade coffee and so forth. So we've seen these certifications. While they are all good in theory, there are also problems with these certifications.

Problems from the practical level about, how do you actually carry out the audit or in the case of the large number of smallholders as, Tonya, alluded to the fact that actually it's pretty difficult to basically provide the level of information that's necessary for a certification to be meaningful.

And there are difficulties also because these certifications don't necessarily get you a massively improved price. So, actually, you're asking for people to commit a lot, often to reduce the amount of coffee they produce because they are being asked to use more environmentally sustainable methods and are not really recouping that enough on the premium on their coffee.

So it continues to be, despite having these ethical certifications, we continue to see a lot of problems in the coffee industry around - how do we make things sustainable in the sense of enabling coffee growers to continue growing coffee and have a decent form of living.

GURU MADHAVAN

So Tonya, help us, look a bit ahead here. How might new engineering modalities or brewing technologies reshape our coffee experience?

TONYA KUHL

Yeah, it's a great question. And, you know, some of the things are, hunting for different genus varietals of coffee in the wild, you know, they just discovered one in South Africa that was just naturally lower in caffeine. So there's all sorts of exploration. Ethiopia, really, you know, the birthplace of coffee, as we mentioned earlier, they've been very protective as it's their country's natural resource.

And so there hasn't been a huge influx of exploration of some of the heirloom varieties that are existing there. And could some of those be more heat tolerant, right? And also have really high cupping quality. I know it's, it's something that people are less enthusiastic about, but, genetic modification of Arabica is another potential or even Robusta to enhance its flavour. As Jonathan mentioned, Robusta is sort of your, low commodity, lower quality, but it's a more robust plant, and it produces twice as much per plant as Arabica.

So can we make that taste better? The other area that is just really an artisanal craft is roasting. So yes, roasters are becoming much more sophisticated in at least tracking analytics and the data of temperature and what's happening. There's not much looking at, off-gassing. So when you roast coffee, you know, you smell roasted coffee, there are things coming off. Initially it's water vapor for the most part, cause it's 12% moisture typically in green coffee, but later on there's CO2 that's coming off, there's all these volatile organic components. People have been roasting coffee for a long time, they have particular ways that they roast it but is that the optimum? So I think there's, there's room for it to really become much more scientific. People are like, “why hasn't that been done?” The challenge is similar to wine. There's so many molecules involved, so many things going on, and we can detect things at parts per million, flavour wise, right?

And so, when you have a very complicated product that you are making, you just don't have the tools or even the standards to necessarily characterize the raw material or what you end up with. That's why this aspect of sensory, and people actually tasting things, is so crucial in this industry, because that's one of the analytics that we have readily available.

GURU MADHAVAN

What's your take, Jonathan? We have algorithms, automation, climate change and other business pressures. And how do you think these are going to change coffee as a ritual and an experience as we know it?

JONATHAN MORRIS

That’s an interesting question, Guru. I'm struck by the fact of how much has become more accessible to me as a home brewer of coffee, for example. Even when I started getting into coffee, and I didn't get into coffee seriously until about the last 20 years or so, there was very little chance of being able to reproduce what I could buy in a coffee shop in my house at any price that was remotely reasonable.

Even buying the consumer equipment that was supplied at that point would make it very difficult for me to produce any kind of approximation of it. So if you think about, can I make myself an espresso? That used to be an incredibly difficult thing to do.

I'm not saying that it's an easy thing to do, but nowadays we do have machines that are in that prosumer band. We have machines that are kind of, you know, hundreds rather than thousands of dollars that enable me to do quite a lot of that work for myself. To the point that, I think it's probably true that if I buy myself a decent quality coffee, I can probably brew a better coffee than I can acquire on a high street where they've probably bought a commodity coffee to supply them. Similarly, I mean, so I'm very excited because I bought a new brewing machine the other day, a new automatic pour-over brewer. I'm sort of setting the parameters on that.

The first parameter that I've just set is the meters above sea level. Now, I mean, the very fact that I have that as a control is incredible. To have that level of equipment and sophistication without having to be super rich anymore.

People have begun to get into that experimentation more. So I think there will be ways in which kind of digital technology and ultimately AI - because there will be AI trying to do those calculations, about what is the optimal way that this coffee is brewed - can possibly enhance our consumer experience. So that's the upside. As a historian and as someone who looks at coffee as a context, I'd say the downside is so much of coffee is about community, whether that's community for consumption. So the coffee shop is a whole different thing. It's not just about the coffee. It is about the coffee, don't get me wrong, you should, you want to have coffee, but It is also about so many more things, in relation to our lives, how we want to live our lives, how we socialize, where we feel comfortable, and all of that. And that's reproduced across the centuries around the world.

So there's a whole other aspect here that becomes interesting. So I kind of feel, you know, if the most wonderful sophisticated coffee machine is actually just located on a station platform, and I go and put a cup under it, actually, that's not an appealing experience, no matter how good that cup is, because that's not what I'm actually buying when I buy a coffee.

GURU MADHAVAN

So Tonya, Jonathan, this has been such a caffeinating conversation, but now comes the time for a big confession. I'm actually a devoted tea drinker. So make your pitch. Why should I cross over to the coffee side?

TONYA KUHL

So I think Jonathan's story about his father and his favourite cup of coffee was compelling. Why you should switch is - tea gets around, it has all this aspect of being healthy for you. Coffee is extremely healthy for you as well. There are tons of studies that demonstrate that drinking coffee not only improves, so for athletes, sports performance. Coffee is a mood enhancer. Coffee decreases your risk for a number of cancers. Parkinson's, cardiovascular disease, type 2 diabetes. So coffee is a wonder drink. I think you should really give it a shot with these, you know, third wave coffee shops are really doing some exotic coffees.

Jonathan and I both mentioned geisha variety. What's famous about geishas is their delicate tea like characteristics. And so, a common flavour that is associated with a geisha is jasmine. And so I think you can get very close to bridging coffee and tea with some of these newer coffees that people are developing and selling.

And I always say, drink it black, like my soul. Okay, that's how I always drink my coffee. And it's healthier for you that way too!

JONATHAN MORRIS

I'm terrified of Tanya if she has a black soul. That's really frightening!

TONYA KUHL

The students like this, you know, because we only serve black coffee in our class.

JONATHAN MORRIS

Ah ok, yeah.

TONYA KUHL

Yeah, so we expose them all to black coffee.

JONATHAN MORRIS

So, Guru, this is interesting for me because I think we might share a little bit of a background here. So, I grew up as a tea drinker, I'm obviously, you know, a Brit, we grew up in a tea drinking household. I didn't really drink coffee at all until I went to Italy to study, and when I went to Italy to study, and kind of had to wean myself into drinking the coffee there because of course that's the very strong espresso coffee And I did it really because I needed to participate in that lifestyle I wanted to be in the coffee bar with everybody else. And it took me a long time to get into coffee.

But what I'm gonna say is my pitch to you would be a slightly different one, and it goes like this. You can become a coffee connoisseur whilst continuing to drink your tea because if you start drinking black coffee the way that Tonya's describing… First of all, try doing exactly the same as my dad - sip it and then we'll let you put the milk in, but sip it first. Just do us that flavour because usually what happens with people who say they can't drink coffee, or they can't stand coffee, is they've never had a decent cup of coffee.

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GURU MADHAVAN

Here's the pleasing paradox of coffee engineering - for all of our technical precision, our carefully calibrated temperature curves, and exactingly estimated extraction rates, what we are really engineering is connection.

So the next time you dial in your grinder or adjust your brew ratio, remember, you're not just making coffee! You're joining humanity's endless quest to perfect this remarkable drink. One carefully crafted cup at a time.

Thanks for listening to Create the Future, a podcast from the Queen Elizabeth prize for engineering and Peanut and Crumb. Look out for new episodes every two weeks and follow QEPrize on social channels, Instagram, Facebook, and X.

The show was produced by Eva Krysiak and this is your host Guru Madhavan.

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