How is coffee decaffeinated?

Coffee Part 3! So we all know coffee has caffeine in it. But what if you want your coffee... without the caffeine? Is that as impossible as wanting to have your cake and eat it too? Thankfully no, we all know decaffeinated coffee exists. But how in the actual HECK do they get the caffeine out? Well, there's multiple ways and they are all fascinating. Check it out.

126 Decaf

Melissa: Hey, I'm Melissa.

Jam: I'm Jam.

Melissa: And I'm a chemist

and welcome to chemistry for your life.

Jam: The podcast that helps you understand the chemistry of your everyday life.

Melissa: Coffee part three edition.

Jam: Ooh, coffee part three,

Melissa: So I'm very excited about this episode. We're going to talk about how coffee is decaffeinated.

Jam: dude, this is awesome. I've wondered this many times.

Melissa: Have you.

Jam: Yeah. I've also looked into it briefly, but I cannot say anything. I ever looked into made sense to me.

Melissa: Well, hopefully it'll make sense to you today.

Jam: Okay. Me too. I hope so, too.

Melissa: Okay. So first off, one thing that I think is really cool about coffee decaffeination is that it is so chemistry

Jam: Nice.

Melissa: and it just kind of reminded me how much chemistry makes things possible for us.

Jam: Yeah.

Melissa: like pregnant women or people who are sensitive to caffeine can still have coffee because of science.

Jam: Yeah, totally

Melissa: And caffeine does have negative effects. It technically is a toxin and it can kill people in high enough doses. So the fact that we can create a drink that inherently is caffeinated without the caffeine is amazing to me.

Jam: Yeah.

Melissa: So I'm very excited about this. I also, before I get started, want to shout out, uh there's uh, I think it's just an individual man who has a background in chemistry who makes infographics he's called compound chem. think we've talked about him before, but he has a great infographic that really helped me process through the different types of decaffeination of coffee and his resources were also really helpful.

So I want to shout out him.

Jam: Very cool. And if this is the first time you're hearing about this and you're like, coffee part three as because we have two other coffee episodes, which are pretty sweet. One's about brewing coffee and the other's about roasting coffee. So they probably don't matter too, too much. The order in this case. But it's be pretty fun to go listen to the other ones as well, either before or after this one.

Melissa: Right, Exactly. You said it was pretty sweet, but it's also kind of bitter because it's coffee. Just kidding. Okay. So here's, what's difficult about decaffeinated coffee.

Jam: Okay.

Melissa: If you want to use something like water to try to remove the caffeine.

Caffeine is soluble in water, which means the caffeine can dissolve in the water. But so do all the things that eventually will react when we roast the coffee bean to make good flavors.

Jam: right.

Melissa: So you're somehow trying to get out a molecule or several of the same type of molecule from this coffee bean. But leave behind all the things that are going to get good flavors later.

And they're all basically made up of organic molecules, carbon compounds. So they have very similar solubilities

Jam: right?

Melissa: to that makes things difficult.

Jam: Yeah. Dang. How do you remove just what you want out of something? Dang. That's crazy.

Melissa: One type one class of molecule. And so. This is also, I think the basic chemistry lesson that I want you to learn about today is that solubility can vary by different molecules in different solvents. So caffeine actually is most soluble in some organic solvents. There's one called dichloromethane, and then it's somewhat soluble and another one called ethyl acetate.

And it's less soluble than those two in water. But if you had something else like salt, it's very soluble in water and salt, doesn't really dissolve in something non-polar like oil.

Jam: Okay.

Melissa: So different substances have different solubilities in different things. And so that kind of is the basis for where chemists would have to come from.

Is can we find a solvent that can dissolve the caffeine and the caffeine has a high solubility in that solvent, but the other things don't

Jam: Yeah.

Melissa: does kind of difficult. And what causes something to be soluble or do be able to dissolve is intermolecular forces. So we've talked about those several times before, so if you haven't listened to that, go back.

I think the very first one we talked about was in the gecko episode, how to get goes climb

Jam: right, right, right.

Melissa: So go back and check that out. If a solvent has similar polarity to a solute, which is the thing that's getting dissolved, then it more easily can take that away. We talk about like dissolves, like, but if it has really different polarity or one's completely, non-polar the other, thing's very polar. It won't work as well. Okay. So. Solubility is the key here.

So if we're looking at something that is very caffeine is very soluble in and it won't touch any of those other pre tasty flavor molecules. Cause we're doing this usually in the green coffee beans.

Jam: Right.

Melissa: One of the best is using carbon dioxide.

Jam: Oh,

Melissa: So normally we know of carbon dioxide as a gas, but, or you maybe know it as dry ice when it's really, really cool.

It's solid. So you see carbon dioxide as gas and carbon dioxide as solid, but we don't where my see carbon dioxide is liquid. It's difficult to get carbon dioxide into liquid in our natural environment. So. There's a way that you can make it into a liquid on purpose.

Jam: Okay, this sounds sneaky.

Melissa: It's kind of sneaky.

So think about what we've learned about gasses, solids and liquids.

Solids have molecules close together with very little movement. As they start to spread out and overcome their intermolecular forces. They become liquid when they get to enough energy. And then if you keep putting energy into it, they'll spread out so much that they become gas.

Jam: Yeah, right, right.

Melissa: So, if you can take carbon dioxide gas and put a lot of pressure on it, you will force the molecules to come close together.

But as long as it's not too cold, it won't freeze.

Jam: it. Got it.

Melissa: So under a high enough pressure, you can essentially get liquid carbon dioxide.

Jam: That's crazy.

Melissa: Yes. So that's another chemistry lesson for you. So there's kind of the one about solubility And then how you can. Think about molecules turning from solid liquid to gas,

Jam: Carbon dioxide is a crazy, like we've talked about in episodes a while ago now, like dissolving carbon dioxide gas into water to make like carbonated water, which is that's already kind of weird and crazy, at least to me. And the fact that it also so strongly resists being like in liquid form is kind of nuts.

Melissa: Yeah, and it, there's a thing called a phase diagram where you can look at the different pressures and temperatures to try and something will be in solid liquid or gas phase under specific temperatures and pressures. And I think carbon dioxide, it looks different than a lot of others. Although I haven't looked at that since I was in gen chem a long time ago,

Jam: yeah.

Melissa: but I seem to remember that.

And I remember waters also being kind of weird because water expands.

Jam: Oh, yeah,

Melissa: anyway, that's just chemistry off the cuff. I don't remember. I don't remember all of that very well. Don't hold me to that. If you're a high school chemistry teacher, I'm sorry for what I've forgotten. Okay. So at high pressures, but not low enough temperatures to freeze, we have this liquid CO2

Jam: Okay.

Melissa: and that liquid carbon dioxide liquid CO2 has a selectivity for caffeine over the other molecules.

Jam: Okay.

Melissa: So you can use that to get out caffeine and none of the other flavors, they basically just, I think they sort of like pump it through is how I imagine it. Um, the green coffee and it comes out with caffeine in the liquid and they can filter out or remove that caffeine from the CO2 and then I can run it through again.

Jam: Got it. Got it

Melissa: So it's a really good option. If you have the money to get the high pressure setup.

Jam: right?

Melissa: Which that's the hard part.

Jam: Yeah.

Melissa: I am pretty sure that's also what they do to extract lavender oil. We briefly talked about

Jam: Oh yeah.

Melissa: when we did the lavender extract episode, and I think they do that for CBD oil as well, because I think, I guess CO2 has a good selectivity for specific molecules,

Jam: Interesting.

Melissa: but I don't know everything about that.

That's. I'd love to be able to tour a plant where they do decaffeination or oil extraction and ask questions about how the CO2 selects that molecule only like why it has a higher selectivity for that

Jam: Yeah. Yeah.

Melissa: is very interesting to me.

Jam: Interesting. That's crazy. So I have a question that started to form my mind based off, out of my like coffee knowledge, that is not scientific knowledge, but just knowing that almost all the decaf coffee that I buy and then roast.

Has been decaffeinated there, a process called Swiss water process.

Melissa: Oh yeah. We're going to talk about that.

Jam: Okay, cool. Cool. I've always wondered like what the heck, but also, I know just from the coffee side, did that is one of the more highly coveted ones to choose because of a few reasons, especially that it takes out a lot of the caffeine more than some other processes.

Melissa: Yeah. So I didn't talk about the percentage of caffeine that comes out.

But I just want to talk about the ideas of what's happening with the molecules, but I will say swift Swiss water decaffeination was my favorite. One of the ones I read about and you'll hear about why,

Jam: Cool.

Melissa: I mean, I think CO2 would be really good except for the fact that it's expensive to set up, but Swiss water decaffeination I think you could even do it.

Jam: Wow. Interesting. Decaf coffee already costs a little bit more because it's gone through, into their process more than other coffee. So I feel like that CO2 process might have to cost us consumers a lot more if it was like more readily available.

Melissa: Yeah.

I could definitely see that costing more because they have to pay for the startup costs.

Jam: Yeah.

Melissa: Okay.

So here are the other approaches and they are all kind of a mixture of using water. And what is known as quote unquote solvent. I think solvent is a dumb name for this because water is also a solid, anything is a solvent that dissolves things.

Even the CO2 is. So as a chemist, I think that's a misuse of language.

Jam: I see.


Melissa: I would call these organic solvents they're carbon-based solvents. So you're using a mixture of water and carbon based solvents of, of different kinds. Okay.

So there's sort of three main uses of the. These things that I would say one is direct solvent extraction.

Another is indirect solvent extraction. And then the last one that we're going to talk about is Swiss water decaffeination.

Jam: Okay,

Melissa: So extraction is a proper word actually here, because we are extracting something from the solid using a liquid. And we talked extensively about extraction. In the very first episode we did on brewing costs.

Jam: right, right.

Melissa: So we are extracting something out of them in direct solvent, which I would call organic solvent extraction. You use some kind of non water solvent, like dichloromethane or ethyl acetate. You have higher solubilities for caffeine than water. So you would be able to get more caffeine and less of the flavor molecules out. So it's similar to the CO2. But it's not ideal because you don't really want to soak your coffee in an organic solvent, organic solvents. Aren't safe for consumption by humans,

Jam: right.


Melissa: So it's not great. They do take a few steps before soaking to make sure that the caffeine is available as possible.

And then afterwards they steam and heat the beans, not to roasting temperature, but enough to try to get all these organic solvents boiled off. And organic solvents do boil off at pretty low temperature. So I would expect there's not a ton of solvent leftover. And in fact, it's regulated by the FDA and anything that is left, I think would be gone with the roast anyway.

Jam: Right.

Melissa: So

Jam: be much higher than the, than the temperatures that they usually boil off at,

Melissa: yes. So I would expect there's not a lot of it. It's still gave me a little like, Ooh, feeling because as an organic chemist, I would never have a container that I used with dichloromethane or ethelacetate and then drink out of it or something. Even if I cleaned it, I would just feel like cross contamination fears.

Jam: Yeah.

Melissa: So I don't love that method, but oh, go ahead.

Jam: especially knowing that, I mean, we haven't gotten them yet, but there's other options. Like if it sounds like you have this option, that's not ideal and make sure that, that part of your brain, the safety part of your chemist brain go, Ooh, I don't know about that. And then, you know, there's options that don't have the same problem.

Melissa: why would I

do that?

Jam: yeah, yeah.

Melissa: And the other thing is organic solvents are not cheap to make. They're not cheap to use up. And then if you're evaporating them off, they're going into the environment and there is chlorine in them, which is contributing to what we talked about on the ozone layer.

Jam: Yeah.

Melissa: and can easily make radicals in the air.

So using organic solvent, when you could do anything else is not ideal. I see how it's valuable because you're not really extracting a lot of the flavor molecules, but I would not use, I wouldn't like this. Isn't my lowest pick.

Jam: Yeah, this one's called. This is the one that's called direct.

Melissa: Direct solvent because you're putting the beans directly in organic solvents.

So the next one, the indirect solvent I think is better, but still not great. Um, because you're still using organic solvents, but you soak the beans actually in water

Jam: Okay.

Melissa: and that water gets out some of the flavor molecules, but also some of the caffeine.

Jam: Okay.

Melissa: And then you can do, what's known as a solvent, solvent or liquid liquid extraction.

So then you take that water with the caffeine and you mix it with the organic solvent, and that will take the caffeine out of the water layer, bring it into the organic layer and leave the flavor compounds that aren't as soluble in the organic solvents behind. And then they spray that water back onto the beans, hoping they'll absorb the flavor back.

Jam: I've heard of this one. I did not know what I was called, but I'd basically in sort of in the coffee world, heard about a process where you basically take a lot of stuff out like that then, then, or the caffeine, and then try to put the stuff sort of back in like the good tasting flavors. So that's what this one is.

Melissa: Yes. And I have questions about how you could actually put the good tasting stuff back

Jam: Yeah, that, that puzzled me too. In fact, I thought it was not true when I heard about

Melissa: No, it's true.

Jam: it seemed like the kind of thing that whenever nonscientists talk about it and be like, I heard this, you kind of

Melissa: Yeah.

Jam: I don't know, but

Melissa: and I did mention this episode to a friend and she said, is that why all decaf coffee tastes so bad? I was like, I don't know, I don't know that it, tastes bad. I've never even had decaf coffee that I'm aware of. So

Jam: Yeah.

Melissa: could be

Jam: I have some when we do Jam's coffee corner. I have some decaf experiences I'll share about at the end, just with my, my perspective on the flavor differences and stuff, but we can get there later.

Melissa: Well, so, and this one actually, Is very common for students to do in a lab. So my students do one with tea, they brew up black tea, and then they do a solvent, solvent, liquid, liquid extraction, where they use organic solvents to take the caffeine out of the tea. Then they boil off the solvent and then they've just isolated caffeine from tea.

And then they like can even test the purity of it in the lab and prove that they've taken only caffeine.

Jam: Oh, wow. That's awesome.

Melissa: It's very cool, but I wouldn't drink the tea that was leftover

Jam: Right.

Melissa: again, though. I know that they are regulated by the FDA. I know that there's not a lot of solvents left, but my science of brain thinks still the water that's going back into

Jam: Yeah.

Melissa: the flavor has organic molecules in it.

And I know are organic solvents and I know they get, they get boiled off logically. I know. It doesn't make sense, but we don't take glassware and then clean it and then use it at home. You know, you just don't do that.

So it just makes me feel, eh, but I know that's a little bit illogical, but I just wanted to share my vibes, but also share that I know that that's not a hundred percent logical.

Jam: Yeah, yeah.

Melissa: So those two are different types of just solvent extractions. And then there's one that uses purely water. And so these are all kind of doing a similar thing where they're taking out the caffeine and then if they also are taking out other flavor compounds, they put it back. But I like Swiss water decaffeination because it makes so much sense and it's cool and creative and like the chemistry of it is beautiful. Okay.

So when you have solvents only a certain amount of things can go into them before it's saturated. So you've probably experienced this with, if you had, if you ever made rock candy and you dissolve sugar in it and you heat it up and heat it up and dissolve sugar until nothing else goes in there anymore, that's a saturated solution.

Actually, if you heat it up super saturated. So there's no other sugar can go in there anymore.

Jam: Right, right.

Melissa: So. In Swiss water decaffeination they soak beans in water and flavor molecules come out and caffeine comes out

Jam: Okay.

Melissa: and they take that water that has flavor molecules, but they filter it to get out the caffeine and they use a carbon filter.

And I'm not sure why it would only take out the caffeine. I have questions about that too. I don't know if it's treated for something specifically. I guess that would be the part that would be hard for you to do at home. Didn't think about that. So you're filtering out the caffeine, but then all the flavor molecules are still in there.

Jam: Okay.

Melissa: So then you take that water that has no caffeine and you put fresh beans in there.

Jam: Uh,

Melissa: those beans aren't going to lose any flavor molecules, because most of that flavor molecules already been saturated, but it's not saturated with caffeine. So the caffeine, while selectively leak out.

Jam: Uh, that is very smart.

Melissa: So smart and so creative, and then you're losing caffeine without losing any flavor because the flavor molecules, I think it would be, I have some questions about why caffeine selectively leaks out, but I think it might be something along the lines of osmosis where, because it's not a fully saturated solution.

If more stuff can come out of it, but only the caffeine comes out, which I think must mean that it's trying to balance the amount of each thing on either side. That would be my guess. I think that's a little bit more biology, but it does make sense to me that there's space in the water for more things to come out and caffeine is the thing that's coming out

Jam: right, right.

Melissa: because we've removed the caffeine and then they can just do that over and over.

Jam: yeah. Yeah. Interesting.

Melissa: I think one batch of beans does just kinda

Jam: Yeah. Get lost.

Melissa: Yeah. Get lost in that. But also I think I would be curious if a little bit of the flavor molecules do come out each time until there's less and less space for the caffeine. Like I wonder how many times they can reuse water.

I'd love to ask someone who does this for their job.

So that's Swiss water decaffeination and there is a version of that where they don't waste that first batch of beans and they spray the water back on as well. So, but I think That is so cool. And so smart.

Jam: is really cool and very smart and seems just like hard enough that I might not try it. Cause I don't know the carbon filter thing.

Melissa: Yeah,

the carbon filter, that would be the thing that I don't know about, but if you could get a carp, a carbon filter that selectively filters out caffeine, you should be able to do this at home. I would think.

Jam: Yeah. I mean, I would try this once. If I, if I could. Cause it'd be

Melissa: But also, how would, you know if it's decaf or not, you need to be able to test.

Jam: true.

Melissa: Does that makes it hard?

Jam: Yeah. Yeah. They have a way probably way better like data about all that stuff. So in ways to measure

Melissa: come do a solvent solvent extraction for you and try to isolate the caffeine in a, in a batch that you've made with this filter and with that, and see, that'd be fun.

Jam: and quickly, it would get. It's like I could have just bought some already decaffeinated coffee, you know?

Melissa: but it is. That's cool to think about, I think this is so creative. I think that that would be the option I would choose as a chemist. It seems the most environmentally friendly. It seems the most, um, you said the most effective for removing caffeine, right?

Jam: Yeah. So at least the information I have is that that removes like 99% of caffeine.

Melissa: And I could see that happening at a pretty low cost as opposed to the CO2 option.

Jam: Right.

Melissa: So very cool. So that's my favorite one.

Jam: Yeah.

Melissa: So I thought that this was very cool lesson because you have solubility or learning about how you manipulate molecules to go from a gas to liquid and extraction on all of these decaffeination.

These are all extractions, so extractions are coming. And so, Yeah.

that's all the science of decaffeinated coffee and I'm sure there's a lot. I missed, it was hard to do all this without,

Jam: Yeah.

Melissa: without going into the weeds. I just wanted to give a brief overview that essentially you're doing something to remove the caffeine from the green coffee beans.

And either you have to find a way to only take out the caffeine or try to put the flavor compounds back.

Jam: That's interesting. And I feel like what's, what's probably cool for us. A lot of people to hear too, is that I've talked to people who I think there's, there's other people who know sort of what part of the process decaffeination happens for a lot of people that, that don't know. And it makes sense because they've never really needed to

Melissa: Yeah. I don't need to

know. I never knew this until I started researching it.

Jam: the people who know I roast coffee, they asked me if I decaffeinate it And I'm like one that's so complicated and hard and I definitely don't. And then they'll sometimes ask it in a way where I think they, I think they aren't sure if I do it, like after I brew it or after I

Melissa: Yeah.

Jam: it, or, you know what I mean? Like or after I roast it all that kind of stuff are there, but it makes sense.

It's not super intuitive to think. When is the right time to the caffeine.

Melissa: Yeah. Well, and I do think part of why they do it in the earlier stages is because if they're using the solvent extraction, then you're more easily able to make sure it's safe later on. But also, I would think that you're messing with less of the flavor molecules because they haven't reacted yet.

Jam: that makes sense.

Melissa: So that would be my thoughts.

I don't know for sure though,

Jam: And then

Melissa: I'm not coffee expert.

Jam: in coffee, snobs, like me are like, well, I want the roasting. And the drinking to be really close together, but I don't want things to happen between there. Cause I want the freshest, you know, once I roasted, I try to drink it within like a week or two. So if I had a decaffeinate after that, that would be complicated.

Melissa: it would take away from the time between the two.

Jam: Yeah. This is very interesting.

Melissa: I'm good. I'm glad you think. It's interesting.

A few people have asked me about it or it got really excited when they learned, we were doing this episode. So shout out to Adriana, Vianet. They were all really excited.

Jam: And two of our friends, and I'm going to try to make, listen to this who are only decaf, they only drink decaf coffee, our friend, Ryan, and our friend Kevin. So I'm going to try to force them to listen to this, even though they might not already know some of this stuff, but, you know, Hey,

Melissa: Well, Kevin is a chemist.

Jam: Yep.

Melissa: So I think he'll really be interested.

Jam: Yeah.

And he might know a lot of this already, but you know, whatever.

Melissa: He knows a lot. He's a smart person. One of those people who just has a lot of information and understands a lot of.

Jam: And researches beyond what most people would research before they make a decision. So he's one of my decaf coffee customers, and he did all his research and he was like, Hey, I'll buy the car from me. If you can get this specific kind, like swiss water process. And I was like, that's great. That's the kind of already know, and like and

Melissa: wonder if he knew it was the mostenvironmentally friendly and had the least exposure to possibly bad things.

Jam: Yeah. Maybe so maybe so.

Melissa: Is he, he worked in a research lab with me for awhile.

Jam: Oh yeah, that's

Melissa: So he knows all about solvents and how gross they are.

Jam: Yeah. Isn't it crazy that I have basically three friends who I see at least like once every week or every other, every other week that are chemists you Kevin, and then our friend Caperton.

It that's nuts.

Melissa: Yeah. You've had a lot of chemists influencing you.

Jam: Yeah. Seriously. It's no wonder that. I think you guys probably were just working on me for a while to come around to

Melissa: Slowly convincing you that chemistry, is awesome.

Jam: Yeah. Yeah. I didn't say a chance. I mean, three against one.

Melissa: Oh yeah,

that is interesting. I guess I didn't think about how many chemists are in our friend group.

Jam: yeah.

Melissa: Well, you're welcome Jam. Do you want to take a stab at being a chemist yourself and kind of telling back the chemistry lessons that you learned from that?

Jam: Yes. Yes. I'll try best. We, that was a lot of chemistry.

Melissa: I know it was hard to, I was about to say boil this down, which is kind of ironic, but it was hard to narrow it down to one main lesson, the way that we are sometimes able to, because there's so much chemistry.

and so many different ways that you can approach.

Jam: Yeah. Yeah. But it sounds like, okay. Basically, it seems like you said four different ways. The first being. The CO2 one where basically, if we could, there's a lot of these, there'll be on ideal about this like cost and stuff like that. But if we could get liquid CO2 and have that be what sort of runs through the beans or have them soak in it or something like that, it is really good at dissolving the caffeine

Melissa: Yes.

Jam: without necessarily dissolving a significant amount of the flavor.

Different, all those, all those different kinds of molecules, which are many in coffee beans that we want to stay.

Melissa: Yes.

Jam: And so that would be a good option, except that it's not super cheap. And on the chemistry side, seems like it would work great

Melissa: Yeah.

Jam: and probably does happen somewhere.

Melissa: Oh, I'm sure. Yeah.

Jam: And then the, you, you lumped the other three into one category.

Um, the. Direct indirect. And what was the third? Swiss water.. Okay. Yeah.

Melissa: is they're all using some kind of solid mixture to extract.

Jam: And using water with other solvents too in not anything like CO2, like not that kind of

Melissa: Yeah.

They're all liquid at room temperature. So that's why I put them all together in my

mind. That's a chemist grouping for you. We're in all of these were soaking beans and liquid and getting the caffeine out. So that's the same to

me, but they do have variations.

Jam: Yeah, it makes sense because I feel like these are ones that probably a lot of people have experienced or had like coffee from one of these three, but I could see almost none of us maybe having an encountered the CO2 decaf

Melissa: right.

Jam: Um, at least I would think, I think the price tag itself would, would raise my eyebrows,

Melissa: It is interesting that they use that for other extractions, like lavender oil and CBD. I've read about that for sure. So I know,

that is done. I just don't have a lot of details on it. So there's somebody who listens to our show who uses CO2 extraction.

Please invite me to your factory or wherever it happens. I really want to. Yeah.

Jam too. We're a package deal,

Jam: Okay, so those other three, the direct, indirect and swiss water, Starting with the direct one, the reason you called the direct is because the different solvents you're using are having direct contact with the coffee

Melissa: right? Organic solvent, specifically, not water they're soaking in organic solvent.

Jam: Okay. And the organic solvent. Is on the chemical level, something that we would not want to ingest, it would not be safe for us to ingest, but it is good at taking out a, in this case, doesn't it take out a lot of stuff, including the flavor

Melissa: No, just the organic solvent itself takes out. it. has a high selectivity for caffeine, similar to.

Jam: Yeah. Okay. So that's the upside of it, I guess, is that it's really good at taking out just caffeine, leaving the flavor stuff behind. Okay. And then the downside. So once that's done and you've already taken out the caffeine, then the problem is how do we make this safe for humans to drink it?

And so they have to boil off those organic solvents. And I hope that most of the traces of it are gone

Melissa: Yes.

Jam: and then they send it to us. And hopefully also it gets removed and roasting, but in general,

Melissa: it's also tested by the FDA to make sure levels are really low. It's hard for me to imagine very much would survive all of that heat, but it's still just, you know, chemistry, safety brain makes me feel like this, but I know that's kind of a logical, I don't want to be a fearmonger. It just is like, my brain thinks I don't eat things that I've touched.

Things that solve in has touched, you know, it just feels. Wrong to some degree. So

Jam: What do you know off the top of your head? Like what things would even make up that organic solvent? Or did you say that to me already?

Melissa: I did mention it. It's it's the two primary ones are methylene chloride and ethyl acetate, and methylene. Chloride is also called dichloromethane ethyl. Acetate is used in actually nail Polish. I think so. And it evaporates really easily. That's why I was good at nail Polish. You painted on and it evaporates and leaves just the polymer behind.

So it does evaporate very easily. All of these of every very easily. It's not like water. If you spill these on the cabinet at work,

Jam: Yeah,

Melissa: I know people don't do this at work when I would work in the lab and I was spill it on the desktop or benchtop with a little bit of solvent, it would evaporate so quick. So it really would not survive long on those beans. It evaporates at room temperature within seconds, a lot of times, unless you do just a ton of it. So it's really very quick to evaporate, so it's, I can see how they do keep the levels low. It's just a mental block for me.

Jam: totally. And we've got other options to talk about too. So then the indirect is the idea of just soaking them in water. Right. Which takes everything.

Melissa: Yes.

Jam: the caffeine molecules and the flavor molecules we all want. And we want to keep,

Melissa: Yes,

Jam: and it's indirect because then they take that water, separate it, right.

For the beans.

Melissa: they, Yeah. They take the water by itself, away from the beans.

Jam: And then they introduce some organic solvents to it.

Melissa: Yes, because they have a high selectivity for caffeine.

Jam: And so they just got the water, they add stuff to, it takes the caffeine away. And then they take the water. That's now just left with the flavor molecules in it and they spray it back on to the

Melissa: Yeah. I think they maybe try to reduce it or evaporate a lot of the water, but it's still, I think that would be, it's difficult for me to imagine the beans.

would fully take that back

Jam: Right, right. Yeah. And then this and that to us and we have potentially some. Maybe it doesn't have a lot of caffeine removed, but might taste a lot less good.

Melissa: Yeah, might they also directly touch the solvent, but the water with the flavors that's put back into it did touch the solvent

Jam: Right, right.

Melissa: again in organic solvents just, aren't ideal to be using because they're not good for the environment, both in the production and in the evaporation of them. So I have a lot of beef with that

Jam: Okay. The, both of those well that one's maybe slightly more safe. Not super.

Melissa: I would say they're both equivalently safe, but not something that I really am going to be like, Yeah. let's do this. Yeah.

Jam: So we have Swiss water process, which is very smart

Melissa: Yes. This one's my favorite.

Jam: and they soak the beans in water first. Right.

Melissa: Yes.

Jam: It removes everything just like the beginning of the indirect, uh, process. And then they filter that water through some sort of carbon filter.

Melissa: That removes caffeine selectively.

Jam: Okay. Removes caffeine selectively. And then that first batch of beans was kind of just to get us to that point, to get us with this. Liquid this water

Melissa: flavor, water.

Jam: water that only has a flavor molecules in it

Melissa: No

Jam: and no caffeine. And then they put a new batch of coffee beans into it.

And now they're in this water that has space for sort of a space for just the caffeine to come out of the beans. But because it's already full of all this, these flavor molecules.

Melissa: Yes.

Jam: It kind of, doesn't take the flavor molecules out of the coffee beans quite as much.

Melissa: Yes. I would a suspect there might be a little bit, but not a significant loss, but I would love to talk to someone and ask them how many times they can reuse that flavor. Water. I would love to know.

Jam: Here's an analogy that just came to my mind

Melissa: Oh yes. I love Jam analogies.

Jam: that may or may not work fully.

Melissa: Okay.

Jam: So this is more specifically just for the Swiss water process. It'd be very hard to come up with an analogy that worked for all of these.

Melissa: Yeah.

Jam: So imagine that first batch, whether you put the coffee beans in and you're just trying to get the water that has the, uh, flavor molecules in it, but no caffeine in it, that'd be almost like, so you have like a car, like a 12 passenger van or something like that.

And at the beginning it's got seats for everybody

Melissa: Yes.

Jam: and you're trying to create a situation where. It has seats for just the caffeine. You do you just want to add some caffeine into riding this



I'm just imagining flavor, like molecules that are supposed to be flavor molecules, like buckled in, from a modeling kit.

Jam: Yeah. So the first just fills the van up and then we go through the carbon filter and it takes just the caffeine out. And so now we have just a van full of flavor molecules. With a couple of seats that were occupied by the caffeine, but they already got off of the previous stop. So here's the way I can think about this that may or may not make sense.

What if basically you could put in some car seats for kids. So the only caffeine fits in there for only kids. So when you pull up and you've got a 12 passenger van, but the only seats that are available are the car seat. Then, sorry, all the other people who want to get on the van, can't only kids can, because those seats are there.

They're installed there and the other seats are all full.


And so we put beans, um, we put this unique type of water that is full of flavor compounds. And molecules has a little bit of room though, but just doesn't have any caffeine in it. And then the caffeine is like, sweet. Let's go.

Melissa: Yes.

Jam: all the flavor molecules are like, man, it's already full.

Melissa: Yes. That's a perfect analogy.

Jam: And then there we go. Did we took just the caffeine out and left a lot of the flavor molecules in the beans.

Melissa: I love it.

Jam: Does that work kind of?

Melissa: That does work. I really liked that analogy. That's a really good one.

Jam: I'm guessing some of the like dissolving stuff isn't quite as like hard and fast as like seats on a van.

Melissa: no, that's a really good way to imagine it. Yeah, that's awesome. And for the other ones, it's like they had the, then with everything filled up.

Jam: Yeah.

Melissa: And they drop off the caffeine and then they go back to the beans and drop the flavor molecules

Jam: Yeah, yeah, yeah.

Melissa: that's a good one.

Jam: we go.

Melissa: Love that analogy. Wow.

You did

Jam: The other thing that wouldn't really be able to be introduced into that analogy, it would be the ones that talk about the organic solvents, because. I don't really know a way that you could factor that into the van analogy

Melissa: The organic solvents only have seats for caffeine from the get-go.

Jam: but also how, how could you add in the like dangerous part or like the

Melissa: Oh,


Jam: like, how about in that case of the van is not safe?

Melissa: Environment. It, it just has bad carbon emissions. The van is out of date for its carbon emissions. So it's bad for the environment.

Jam: in that case, you're kind of like, wouldn't, we all be better off by leaving this van

Melissa: We'll use a different van. Uh, van that has seats for everybody.

Jam: And has more up-to-date emissions stuff or whatever.

Melissa: And in the solvent water extraction. What they do is drop off the caffeine molecules into the bad emissions van.

Jam: yeah,

Melissa: And then the good van goes in backs and ups off the water, the flavor molecules back at the, at the coffee beans. We did it.

The only one is CO2, which is kind of like an airplane.

Jam: yeah, yeah.

Melissa: CO2 is an airplane that only has room for caffeine.

Jam: Yeah. And it's yeah, it costs more.

Melissa: Yeah.


Jam: You don't want to ride in the Greyhound or the van or whatever, or don't wanna take the airplane and it's

Melissa: That was good.

Jam: most of us are gonna take the

Melissa: Yeah, most of us are going to road trip. It. That was hilarious. That was so good. I wish we had thought about that earlier on. Oh, that was awesome.

Well, this episode's already a little bit long. So normally we do a happy thing from our week, or I really want to hear your coffee, corner, your decaf stuff, but let's go ahead and wrap it up. And then, um, for our Q and R, this gives more exciting things to look forward to in Jam's coffee corner, during the Q and R.

And you can hear about our weeks and everything good.

Jam: Yes, absolutely. And it makes sense because there were like sort of four different chemistry lessons in this.

Melissa: Yes. A lot of chemistry for your life.

Jam: Yeah, yeah. Almost no way to make it shorter. So

Melissa: Well, thanks Jam, for being coming of that awesome analogy and being excited to learn about decaffeinated coffee.

Jam: Dude, pulled it, pulled it out last second. You know, I almost didn't have anything, but.

Melissa: That was really good. And thanks to all of you listeners for coming and listening and learning about coffee and being so hype about this series. That's been really fun to see.

Jam: Yeah, it really has. And we really appreciate you guys when y'all send in your questions or ideas or thoughts or whatever. So if you have those, please don't hesitate to send them in. You can send those to us on Gmail, Twitter, Instagram, or Facebook at chemforyourlife. That's chem F-O-R your life to share your thoughts and ideas with us

if you'd like to help us keep our show going and contribute to cover the costs of making it go to and donate the cost of a cup of coffee. If you're not able to donate, you can still help us by subscribing on your favorite podcast, app and rating and writing a review on apple podcasts.

That also helps us to share chemistry with even more people.

Melissa: This episode of chemistry for your life was created by Melissa Collini and Jam Robinson. References for this episode can be found in our show notes or on our website, Jam Robinson is our producer, and we'd like to give a special, thanks to S Navarro and V Garza who reviewed this episode.

© For Your Life 2022, All rights reserved.