#46: The Potential of Controlled Fermentation Through Yeast Inoculation | Panel Discussion | Expo Lectures 2018

Join us today for an exciting panel made up of microbiologists working to develop strains of yeast specifically designed for coffee fermentation and leading coffee producers. In this discussion, they deep-dive into the ongoing research in coffee processing using selected cultures and the analog between scaling microbiological technology in the traditional worlds of wine and coffee.

This panel discussion recounts the experiences of panellists Aida Batlle, Rachel Peterson, and Tim Hill in France in October 2017, when they spent a week exploring yeast selection, production, and characterization in an effort to improve global knowledge on the organism, and also get alignment with the application in coffee (such as timing, preparation, sensory demands, waste streams, etc.).

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Table of Contents

2:30 Introduction to yeast inoculation and the panelists
8:00 A discussion on what are your sensory goals when working with coffee and how yeast plays a part in that.
10:45 What work has been done to explore different flavor characteristics of coffee using yeast?
24:30 What strains of yeast are being explored at the moment
26:35 What coffee defects can be avoided using yeast inoculation
30:30 Is there a difference in the fermentation process for coffee produced according to different agronomic practices?/
39:30 Audience Q&A/
59:00 Outro

Episode Transcript

0:00 Introduction

Heather Ward: Hello everybody, I’m Heather Ward, SCA’s Senior Manager of Content Strategy and you’re listening to the SCA Podcast. Today’s episode is a part of our SCA Lectures series, dedicated to showcasing a curated selection of the extensive live lectures offered at SCA’s Specialty Coffee Expo and World of Coffee events. Check out the show notes for relevant links and a full transcript of today’s lecture.

It’s EXPO week! We thought we’d release a super interesting lecture from our 2018 series to inspire and excite you as you make your way to Boston. Still not sure what to do with your time at Expo? See the full schedule of events, workshops, lectures, and parties at coffeeexpo.org.

Join us today for an exciting panel made up of microbiologists working to develop strains of yeast specifically designed for coffee fermentation and leading coffee producers. In this discussion, they deep-dive into the ongoing research in coffee processing using selected cultures and the analog between scaling microbiological technology in the traditional worlds of wine and coffee.

This panel discussion recounts the experiences of panellists Aida Batlle, Rachel Peterson, and Tim Hill in France in October 2017, when they spent a week exploring yeast selection, production, and characterization in an effort to improve global knowledge on the organism, and also get alignment with the application in coffee (such as timing, preparation, sensory demands, waste streams, etc.).

And, although you aren’t able to join through this medium, this session also included a tasting of chocolates — a control sample and two samples inoculated with different yeast strains — to prove that yeast can bolster taste.

Please join us in welcoming today’s panel: Aida Batlle of Everest S.A.; Timothy Hill of Counter Culture Coffee; Rachel Peterson of Hacienda La Esmerelda; Benoit Bertrand of CIRAD; Laurent Berthiot of Lallemand; and Zachary Scott of Scott Labs, Inc.

Also, I’ll be jumping in throughout the podcast to help you follow along.

We’ll let the moderator – Barista Magazine’s Sarah Allen – take it from here!

2:30 Introduction to yeast inoculation and the panelists

Sarah Allen: Good morning. Welcome and thanks for joining us for this session, The Potential of Controlled Fermentation through Yeast Inoculation. We’ve got a lot to cover in a short time. So, I’d like to Jump Right In. I’m going to start with a story, our story. The one shared by the people seated on the stage. Ours is one of many stories of how yeast inoculation with coffee fermentation is being researched, developed, explored and experimented with.

Many of you have already heard of this practice. Producers around the world are playing with the technique which enters the processing system at the fermentation stage and where a few years ago there were only a handful of roasters playing with the application. Now, there are more, many of whom are working directly with producers at their trials. The story of the people on this stage is one of many. What we will talk about today isn’t meant to be the one and final way to understand and use yeast, but it’s a pretty extraordinary window into which to view the most current practices and findings.

In October of 2017 our group embarked on a trip around various wine-growing regions in France for myriad reasons., and yes, we did drink wine. But we did so in an effort to learn something. A carefully chosen group of coffee producers, which is Rachel and Aida and one of the world’s leading coffee quality directors on the roasting side Tim Hill joined microbiologists yeast mongers, wine consultants and viticulturists for five days of education. The learning opportunities of the trip extended to all involved. The coffee professionals studied the potential of yeast applications and the microbiology team extrapolated what the coffee industry needs from coffee specific strains of yeast in order for them to be adopted as viable and usable useful processing tools.

When the trip concluded no one had arrived at any hard and fast conclusions. We left with more questions than answers, but that’s a good thing. Yeast inoculation and coffee for fermentation is in its infancy truly. That’s part of why it’s so fascinating to track how development and results of practices and strains are unfolding.

This session will continue now as a panel discussion. But before I have the presenters introduce themselves, I’d like to tell you a little bit about your chocolate samples. As you may or may not be aware countless foodstuffs are fermented and chocolate is one of them. The microbiologist at Lallemand, which is a global leader in the development and production of yeast and where we visited in Toulouse, France has worked for years with various strains of yeast developed specifically for chocolate. You have a control sample and actually I’d like Laurent to tell you a little of the chocolate because he made the chocolate. So, can you give them a little information?

Laurent Berthiot:     Okay. So, the three samples that you have the A is the control, the B it’s one yeast and the C another one. So, the chocolate was made, the fermentation was made in Peru in Tingo Maria in a small Co-op and I’ve made the chocolate in Toulouse like two weeks ago. That’s it.

Sarah Allen:  Okay. So just pay attention to the letters on the bottoms of your cups. The A as Laurent said is the control and the B and C are different yeasts.  So, see what you think. it’s all about playing with how you can taste the differences. Now I’m going to ask our panelists to introduce themselves briefly. Please tell them your expertise and also a little bit about your personal experience with yeast.

Aida Batlle: Hello, my name is Aida Batlle. I’m a coffee producer from El Salvador ,5th generation, and we’ve been experimenting with yeast for four years now.

Laurent Berthiot: So, Laurent Berthiot. I’m French, working for Lallemand and I’m in charge of this technical support for coffee and cocoa producer about fermentation, so, using yeast.

Timothy Hill: My name is Timothy Hill. I’m the Director of Coffee at Counter Culture and Aida just lied, we’ve been experimenting with yeast for six years. Starting in a bucket, before I think anyone was really doing anything, but just trying to figure out what it is.

Rachel Peterson: I’m Rachel Peterson. I’m a Coffee Producer from Panama and we’re from Hacienda La Esmeralda in Panama. We did a little bit with yeast last year, but this is our first year to do more experiments with yeast.

Benoit Bertrand: I’m Benoit Bertrand from Cirad. I’m head of a research unit working on breeding disease in coffee. And I have small experience in yeast but some people working with me have worked on the yeast.

Zachary Scott: And I’m Zachary Scott from Scott Laboratories. Our company has been working in the wine industry in the US for quite a long time. Since 1934 where we inherited the yeast library from UC Berkeley. So, we’ve been with yeast for a long time and the industry really invited us to start experimenting with them in coffee. I think the first one was in 2012, and we’ve really just been learning and getting feedback and trying to relate that with their Partners at Lallemand and keep learning from the industry as to what they need to happen.


8:00 A discussion: What are your sensory goals when working with coffee, and how yeast plays a part in that? 

Sarah Allen: Thank you. I’m going to start the discussion with some questions for our panelists. There will be time at the end for Q&A as well. So, we’re going to start simple here and this one’s for Tim and Rachel and Aida. So, just some general thoughts on what your primary sensory goals are in the coffee that you produce and or buy and how does processing method impact your coffee sensory and how have you found processing with yeast impact sensory? So, that’s a two-part.

Timothy Hill: I guess I’ll start. One thing that I’ve thought of over the years is unless we’re scoring a coffee 100 points, no coffee is absolutely perfect. There’s always something to manipulate, to change, to figure out what you want to get more out of that and, that’s kind of where yeast has come into play a little bit is, if the coffee is a little bit vegetal, can you clean that up? Can you sweeten that up? Can you incorporate more fruit? Can you ferment longer without having over fermented flavors? How much of that can you control? So, to me it’s looking at what you want to achieve out of a coffee where it’s highlights are, where its benefits are and how you can manipulate that through processing, roasting etcetera.

Aida Batlle: For me as a coffee producer, we’re always looking to see what we can do, how we can improve. And this trip to France, and even before then I’d heard about yeast in general and knew the potential it had in other Industries, and we wanted to see what and how it would change profile for us.

Rachel Peterson: We wanted to see, we wanted to experiment with different varieties and different elevation of coffee to see what yeast did to the cup profile on 1100 meter Catuai and a 1400 Catuai and a 1600 meter Geisha and 1800 meter Geisha and how it affected just every part of the sensory, like the acidity, the mouth feel and if it polished out things that we didn’t like or if it enhanced things that we liked. So, it was mostly an experiment to see if it was something that would be viable in a larger, we did very small experiments. So, it was something to see if it would work for larger quantities eventually and so we did different experiments on that type of thing just to see how it affected the different varieties and the what it did at different elevations.

10:45 What work has been done to explore different flavor characteristics of coffee using yeast?

Sarah Allen: Great. So, starting from that point and the rest of the questions are for everyone, just jump in when you’ve got something to say. How much exploration has been done in yeast to distinguish different characteristics of similar coffees?

Laurent Berthiot:  Okay if I talk only on my side a lot. I’ve made two years of experiment now around the world. Maybe more than 40 different farms, different size and what you…

Sarah Allen: What countries?

Laurent Berthiot: What country? We’ve been in Kenya, Ethiopia, Tanzania, Ivory Coast.

Timothy Hill: We sometimes say it’s easier to count the countries that we haven’t done trials in.

Laurent Berthiot: A lot, even in Central America, most of them Brazil, Asia, Lajos, India. So, it’s quite hard to say exactly how many but what we clearly see is that you have the improvement of the quality, but you have also a modification of the process. I think it’s also very important and the consistency that you can bring to the coffee, more than.

Zachary Scott: And the word that I continue to use is intention. So, just as there’s intention and our farming practices, there’s intention in our processing practices certainly in our roasting practices. This is a step production that in many Industries gets overlooked because we can see the tractor, we can see the plant, we can see the machines, we can see the roaster, but we can’t see the microbes without looking under a microscope. So, we somehow skip over the fact that this is a, you mentioned that we’re just starting in yeast inoculation. Those words were chosen perfectly because we have just started in yeast inoculation to inoculate with intention. But the yeast has been there. We just don’t know what it is each time or where it is or where it came from If its native, if it’s exogenous. So, I think that this whole process of intention is really where people are getting involved and I think that echoes what Tim is saying too and Aida as well. And then also just the curiosity that Rachel talked about is what’s the interplay of everything and all that’s been done. This is just a new area where people have a tool.

Sarah Allen: Laurent, can you talk a little bit more about that intention and how you have listened to producers when you’ve been doing these trials and Zach you can jump in too. It’s just because, yes, there is a lot of potential for changes in cup profile, but it also serves a lot of other different purposes like potentially extending shelf life. And so, in your trials what how have you worked with producers to solve for their particular problems?

Laurent Berthiot: I guess most of the producer have already the same intention, is just improve quality. But we try to show them that quality is a point, consistency is another one, the process management is another one, shelf life is another one. But, as Zach says, we are at the beginning of all of this information. We see the impact of using yeast in the fermentation, but we keep working on with the Cirad, with many Research Center like the ones in Vietnam just to understand exactly what happened on coffee and how we can help the producer to manage all the stuff. It’s not only quality. Quality is kept score.  It’s everything.

Sarah Allen: Right. I’m actually wondering at this point if maybe we could have Aida since you’ve done so many experiments just sort of like run through what it is when you’re, from start to finish of an experiment that you’re doing with yeast like when Tim comes down, can you run that through with the rest of these?

Aida Batlle: Okay, so when someone like Tim comes down. Depending on which yeast we’re going to use. We wake it up and then add it to the fermentation tank. We add water. It has to be at least 15 degrees Celsius, introduce it to it and then wait 20 minutes and then add it to a fermentation tank.

Sarah Allen: And what’s the ratio?

Aida Batlle: So, it’s 50 grams of yeast per hundred pounds of cherry.

Sarah Allen: Okay, and then what about agitation and?

Aida Batlle: Yes, you agitate it and then you added to the fermentation tank and you let it sit. And we’ve gone as long as 96 hours in a farm in Costa Rica that wanted to experiment that was at 1500 meters and so was the mill. We actually extended it to a 120 hours of fermentation.

Sarah Allen: And could you just touch on some of the of the more sort of wild ways that you’ve played with it with the snipping and with spraying it on the tables and stuff like that.

Aida Batlle: So, we’ve been with we have been playing with it. We had Lucia Solis come down and she’s helped in that regard as well, and we sprayed it on natural coffees as they’re drying. We did five applications every 12 hours. We’ve also done this year, which I haven’t cupped yet in underwater or yeast fermentation for natural that we extended to 18 hours. We’ve done 36, we’ve done a lot of different processes. Just trying your mouth.

Sarah Allen: Okay. Thank you. And on that, I’m sorry actually Zach

Zachary Scott: If I can chime in it’s I think that’s an important point which is that the yeast is just one of the tools. There’s no monolithic way to use yeast. If I use the analogy of whether its beer or its wine, every winemaker, every brewer has their own way that they make their own product special. And the yeast is really part of that process. It’s synergistic to the fruit that’s coming in and to the process that’s applied. So, just by using one strain of yeast you don’t get the same result every time if these other factors are changing. So, how you process it, what elevation you get it from, what the variety is and that’s for example Benoit and their work on cultivar development. That’s very interesting to see. All these new cultivars that will come online. What’s the interplay? What are the precursors for aromatics for all flavor development?

Sarah Allen: Can you and Benoit elaborate on that a little bit?

Zachary Scott: You want to talk about your program?

Aida Batlle: Yeah.

Benoit Bertrand: Maybe before, to give you my point of view from an ecological point of view. Fermenting of fruits is something very natural. In the wild all the fruits finish to ferment and this fermentation is due to natural yeast. And those natural yeast doing esters that are volatile compounds that can attract insects and the insects eat the fruit to liberate the seeds. It is something very natural. So, what is very interesting in studying the yeast and for the fermentation of coffee? Is from a scientific point of view, is that the yeast producing some esters and those esters at very, very, very low quantity. At, for example 10 ppm to 40 ppm can give you the difference on sorry profile. So, the difference between using yeast or not using yeast is a fabrication of some ester but at very low concentration and but the modification is also the sensory profile could be huge.

Sarah Allen: You want to do?

Aida Batlle: I just wanted to add something. I think it’s important to state that without the roasters supporting programs like this, it is very hard for producers to do it because there is an additional cost. As a producers, I would recommend, like Rachel said and how we started, five gallon bucket trials see how you do with it. But again, it’s very, very important for roasters to get behind it so they can support producers in helping them experiment with it.

Sarah Allen: Actually, that leads to a point that, one thing we discussed on our trip which is it’s because it has the potential to improve cup quality, it might not necessarily be a tool that an elite producer would use as much as perhaps a producer with a lower ground farm who wants to improve their quality and when you’re talking about firms that might be struggling with their cup profile. They might not be the ones who have a lot of extra money to use on the experiments and the yeast itself. So, I think that’s a really good point to make. Anyone else to talk about more of the impacts they’re using. Tim?

Timothy Hill: Yeah, I mean one thing I’ll add in the just like in the onset of the experience and working with yeast and what it can do is I think a lot of people come into this thinking like “I’m going to use yeast. I’m going to make this incredible product.” And I’ve been buying coffee for a little over a decade and I’ve gotten to a lot of experiments with that in mind. And went into that with yeast the very first year that Aida and I worked with yeast. We were just trying out champagne yeast and all these different things that we had no idea what they would do and most of them were great. Most of them were actually below the standard of what we’re working with in the first place, but that didn’t stop us from working and continuing to do that.

And I think we’re at this phase right now where we have seen coffees that are significantly better in cup profile and have change it significantly, can bring a whole different dimension to it. But we have seen products that are below the standard and I think as it’s good to keep in mind that as producers in the room or roasters that want to try this that you can’t use anecdotal one-time experiences as your be all and end all of what you’re looking at. Because yeah, we’ve seen things really incredible. This is the start. There could be really amazing potential in some of the yeast but we’re also working with a very limited number right now. We have, how many wine yeasts do you have for producers?

Zachary Scott: About 70 for wine and that’s just what we carry on the shelf and we have three for coffee so, it’s small.

Timothy Hill: So, that’s kind of where I’m coming at this from my perspective where I’ve seen really incredible coffees. Not as good as they have been in the past when I’ve used yeast, but I’ve also seen coffees that have significantly improved and I’ve been able to manipulate a profile in a way that I’ve wanted to manipulate it, it was intentional.

Zachary Scott: If I can. And I think it’s important to remember to that what gets me really excited about the utilization of yeast and coffee is not a better score. It’s a different profile just to elaborate on that point and a recent trial that was done. A lot of replications tasted by a lot of people. There was a scoring increase and that’s nice. What got me excited was that there was enough statistical significance in a couple of the different flavor profiles that were reported back by I think about 16 different cuppers that was well outside of the standard deviation that, for example in this one strain it was fruity was the main characteristic that it was pushing. If you don’t want fruity in that cup for that specific variety of coffee and that specific style, that’s probably the wrong strain. And I think that that’s what’s important to remember too is that yeast is not monolithic. You have these strains that are all the same species, different varieties just like different cultivars of coffee.

But again, it’s these very small phenotypical differences, production of esters or enzymatic activity that’s resulting in the aromatic profile changes. So, we just started on this and 20 years from now we can have a much different conversation. And again, hopefully we have more tools to let you have the intention to arrive at the final result you want. Right now, we just have very small guide posts along the way.


24:30 What strains of yeast are being explored at the moment?

Sarah Allen: On that note. Can you discuss a bunch? They’re what, 40 different strains that are in trials right now. Is that about right?

Laurent Berthiot: It’s a bit less than that, about 20 extra.

Sarah Allen: 20, okay. And tell us what the intention is of those strands. Are you developing them for specific varieties, for specific regions?

Laurent Berthiot: No, the idea is now is just that we try to focus on having different type of profile. So, these three strains that we have are very different, but we try to have something like pushing more the nutty flavor or the chocolate flavor. So, we try to just look at the collection that we have, and we know some of them are working more on chocolate, on nuts, on fruits, on flowers. So, we just try to use them on coffee and see what happens. That’s the first step. Then we’re going to have another project about selecting one of those 20, maybe six and use them on six different variety.

Sarah Allen: Okay.

Laurent Berthiot: Just to see if each one has a different impact regarding of the variety of coffee. That’s the idea. I mean every year, we try to have two or three different type of investigation just to you. Improve the number of profiles that we can modulate with yeast.

Sarah Allen: So, how far would you say you are from releasing additional for commercial use besides those three? Aida definitely wants to know this.

Laurent Berthiot: I mean as Benoit says yesterday for genetics. It takes time to make investigation. So, lucky with her it’s not going to be like 25 or 30 years of investigation. But, I guess in two years we’re going to have more. Probably during this year we’re going to have more yeast too. I’m expecting the coffee right now. So, I just want to cup them before sending some samples to Aida, our team or Rachel just to make more trials.

26:35 What coffee defects can be avoided using yeast inoculation?

Sarah Allen: Okay. We’ve talked a bunch about improvements to coffee, but can you discuss if there are any defects that you’ve seen that it could be avoided through using yeast inoculation.

Zachary Scott: Yeah, the most common types of experience we’ve seen and as you’ve heard we’ve done many at this point, but most common is that the negative result is that there’s not a significant difference and I think that can be explained in a number of different ways. One of them is just if the precursors for the aromatic compounds that that yeast may be more adept at developing weren’t there. So again, the yeast is not really making these flavors in a vacuum. They are really transmuting it from the precursors that are available on the fruit. So, that’s one of the more common results of the negative aspect there is you spend money on inoculating with yeast and didn’t get a result. But even in that same situation what we’ll find is that if multiple replicates are done we’ll see it’s 82, 83, 82, 83 between control and treated. Ones in 83 and ones in 82, vice versa. So, not much difference and then all of a sudden there’s a control that says 71. And why is it a 71? It’s a 71 because there was a defect, and there was a defect that was phenolic, or it was winey.

So, one of the benefits of again inoculating with intention is, you know your organism and you know the microbe that is in the ferment and specifically you now know the microbes that are not. And, one of the benefits of Saccharomyces and one of the reasons why we focus on that above all other types of organisms right now, it’s not to say we can’t expand it to other non-saccharomyces yeast or bacteria. Saccharomyces is very portable. It can dry, it’s easy to move around. It doesn’t need to be refrigerated. So, it’s very easy to use very easy to get through the logistical pipeline that is the coffee industry. borders and customs aside. But the other side is it’s very good at crowding out an ecosystem.

So, when it gets into that ferment at the rates that we’ve inoculated it implants fully which is to say that it is the one that is doing the fermentation and it basically is crowding out other organisms that could potentially spoil the ferment. And that work was initially done with the Cirad in Nicaragua. That first step that we go through each time we engage in a new process, which is what we’re adding doing the work. And I think that from a consistency standpoint is important. That also from a future compliance standpoint I think is interesting too. In the wine industry we have a product that no human pathogen can live in wine. It’s only consumed by non-pregnant adults.

So, it’s not exactly a high-risk product and yet at the same time. I think the same as the coffee industry. FISMA is here, the FDA is here, and they are asking us a lot of questions and they really want to know chain of custody. Where did your food come from? Where is that? What happened to that product that’s about to go into someone’s body. And I think if looking at this industry, I think we’re going to be able to say it’s like we bought it from somebody that made it somewhere else and it came in. But, don’t worry we roasted it, we have a kill step. I think that’s not going to protect us as much as it has in the past. Not in wine, not in coffee, not in beer. So, I think again knowing your process, knowing what is processing your products is important.


30:30 Is there a difference in the fermentation process for coffee produced according to different agronomic practices?

Sarah Allen: This was a question that Benoit suggested. That was a good one. Do you think there may be differences in the fermentation process for coffee produced according to different agronomic practices?

Benoit Bertrand: No, I have no idea if there is. If I understood well your question. If the agronomic practices can have an impact on the fermentation?

Sarah Allen: Yup.

Benoit Bertrand: No, I think that only the ripening of the fruit. Yes, it’s true, you have to harvest fruit at a good stage of maturation. It is very important for the post-harvest process and it is important also during the fermentation and during the fermentation with the yeast. One thing that can do the yeast is to improve the microbial kinetics during the fermentation. So, you stabilize even when you harvested some green fruits, you can have a better fermentation using yeast. This is right. But the only way where we have, we’ve only seen, to my knowledge between agronomic practices and yeast. But before, maybe in the future we can imagine to put yeast before harvesting, on the fruit. Why not? Inoculate before, it’s a crazy idea. I don’t know if it can be used but it could be an idea to start the fermentation before resting, maybe. Something we can test.

Sarah Allen: I’m looking at the, oh, go for it, Tim.

Timothy Hill: The agronomic practices. I think there’s potential in different things certainly the fruit. To me, I’m also really interested in the ecologies. A lot of times I’ve seen, we talk about reducing vegetal flavors and coffees and increasing body, getting more sweetness out of products. But with yeast we’re actually in discussions about reversing that. What does it mean for places that have historically had very fruited coffees, very winey coffees that can’t control that because of climate. So, I think of particular areas in Guatemala, I think many people in this room have had that one region in Guatemala, maybe that one Co-op that is really high in elevation. It’s very cold and the fermentation times range from 32 to 48 hours and they can’t really control that to remove the fruit. And so, can yeast can actually reduce that fruitiness? Can you control that process a little bit more? And so, I’m kind of interested in those places that you have less control over their product and less control over that fermentation step.

I think yeast could have a really big impact in terms of the ecologies and the climate in terms of what you can do and these places that sure it’s a fruity coffee you may love that fruit, but not every buyer wants that. Can you give access to farmers that maybe there’s someone that avoided that coffee? There’s even ideas of I don’t know how far we’ll take it but, on the fruit was a really interesting comment about potato defect in Rwanda Burundi. It’s thought to be a bacteria. Can you use yeast to crowd out this bacteria in the environment so that it’s not inoculating the cherry? I think there’s very big interesting ideas that can come from that.

Benoit Bertrand: Something interesting also is that the fruits, the coffee fruit is a drupe. That means that it is not able to ferment if you do not cut the fruit so there is the entrance of microorganisms. If you left the fruit on the trees, the fruit is conservative during many weeks if there is a climate is not so rainy. So, it is interesting for me and maybe for the future also to refrigerate. Because when you harvest the coffee, the fermenting begins because there is inoculation of yeast during the harvesting. So, you are starting the fermentation at this moment. So, maybe it was a for what I proposed, this crazy idea to put yeast before harvesting but the second maybe idea would be to refrigerate the fruits when you want to do a very special coffee to refrigerate the fruits during the transport, just after the harvest for example.  It could be an interesting trial. If you can finance me for that, it could be.

Zachary Scott: There have been some trials that are along similar lines where we’re taking non fermentative yeast and we’re using those as a bio protectant and solely to allow for extended time but without actual fermentation. I think this is not our primary axis of inquiry because again, we start getting into much more challenging strains in terms of logistics and being able to, and more expensive strains. So, I think that really again it’s about opening up this world of something that has been going on for hundreds of years. But really investigating what’s going on, understanding what we want our results to be and also ultimately what the consumer results are.

In the wine industry or in the beer industry you can take the same base and make it in three different styles. It’s still representative of the base, but it has three different styles. So, it would allow someone like this Co-op, yes to produce a more fruity and a less fruity so that I think it starts giving more brand and intention to the farm and the mill step so that when they’re selling their wares to the roasters, it’s giving the roasters now more of a portfolio of flavors to choose from.

Sarah Allen: Do you want to add to that?

Benoit Bertrand: No, but it’s not a joke. But it’s false scientific point of view. Also, it’s very important to understand what happens between the beans and the yeast. It is clear that the yeast is synthesized esters. But, all esters are transported into the bins.  Is it an active transport? It is a passive transport because there are small molecules. So, there is the ground tool to develop a lot of science and a lot of interesting scientific studies and it is very exciting for scientist what happens with those first experimental trials. And what is interesting also is that this company is ready with commercial yeast so we can do that in different countries, in different varieties, in different environment because the way that you use the yeast is very simple. That was very difficult before but right now is very simple. So, using those yeast we can really experiment in a lot of ways with new varieties or all those varieties in different environment.

Laurent Berthiot: Just to complete what Benoit says about the interaction between the liquids in the yeast and the bean how the esters can go into the bean or what is the migration of the component? At Cirad, there is a young student. She just started PhD on that. So, we expect to have some information about all that stuff during these 3 years of PhD and we’re going to publish a lot with those results.


30:30 Is there a difference in the fermentation process for coffee produced according to different agronomic practices?

Sarah Allen: Again, it’s just at the beginning. I think this would actually be a great point to open it up to audience questions. We’ll start with you.

Audience 1: If different starting materials impact fermentation and different agronomic conditions impact the fruit, would agronomic practices impact the fermentation?

Benoit Bertrand: You are right. The agronomic practices and the variety can impact the composition of the fruits. For example, can impact the sucrose level and/or the fatty acid composition and we know that the sucrose and fatty acid composition are a key component for the fabrication of the esters. Because the ester is fabricated by organic acids or by medium fatty acid chain and the yeast is hitting the substrate, the mucilage of the coffee beans to fabricate those esters. So, it is very important, and we know that you are right. As a farming system and also agronomic practices has an impact on the composition of the bin. You’re right.

Audience 2:    How does temperature and pH affect yeast inoculation?

Zachary Scott: Maybe I can address the temperature first and I’ll incorporate in the nighttime harvesting. That shouldn’t really impact what the indigenous flora is coming in. It will impact the temperature and I think that because of the vigor and because of the consumption of sugars and the metabolites, there’s a pretty broad range of temperature that is acceptable for the yeast. So, starting at around 15 °C is fine. And then I would try to keep it under 25 C. But again, the easiest way to achieve that result is actually to start low in temperature and then it will slowly rise over time, but not very rapidly. Because the amount of sugar that’s available and the vigor of the ferment is not like it is in wine or beer where there’s a lot of available sugar and there’s a lot of heat that’s generated and then pH I’m not aware of a limiting factor.

Laurent Berthiot: On all the experiment they’ve done I’ve never seen any impact, real impact of the pH. I can’t notice it, from the temperature yes, but the pH no. But just to complete the question about harvesting at night, I think it’s also a way to be sure that you, how Zach says start at low temperature and as Benoit said before that just when you start the harvesting, the fermentation starts in the cherry. So, doing at night you have low temperature so the fermentation can’t start easily. So, it’s just a way to calm down the fermentation and start it exactly what you want.

Benoit Bertrand: And probably the lower temperature you have, higher altitude can explain the better quality of the coffee. So, maybe and I think that we have never experimented with this. That means that, for example harvest coffee in higher altitude and ferment the coffee at lowest altitude with higher temperature or in comparing that with coffee harvested at high altitude and fermented at low temperature to see if there is two differences in terms of quality. But, it could be another very interesting study. So, we can conclude really that studies are starting and pave the way really to other scientific studies. It’s very exciting.

Audience 3: In Zachary Scott’s work, one strain of bacteria outcompeted other strains. So, did his work test concentrations for microflora prior to inoculation and using control such as sulphites?

Zachary Scott: So, there’s a lot of questions. So, I’ll tackle them. But if I forget one remind me. So, kind of starting on the indigenous populations. I was thinking about it before I got up here because it’d probably be good to remember the name of the city. There were two papers that were done that kind of did a nice profile of what was active in a ferment. One was done in Africa, I believe the other one was done in Central America. But they were just in the literature that we were looking at when we first started having more intention in this, there’s my word intention in this industry. And, when we first started it was some work that we did on a real base level in Nicaragua as well.

Lallemand’s entire experience, my experience in yeast has all come from isolating strains from the crops that we’re impacting, and I think that that’s going to be a very natural evolution. The difference is we have a hundred year head start in things like wine. We’re just starting now because not only do we need to isolate we need to characterize. So, we need to see what was actually giving that. So, if you have the best fermented coffee, and so we show up and you’re really excited because you want to see what was doing that fermentation. First we have to see if we can isolate it which is a challenge unto itself. Then once we do that, then we have to validate that it’s implanting regularly. Then we need to validate that it can actually be dried and can be used in other places.

So, I think that’s probably more in that 10-year scope being able to get to that point but a huge target of ours as well. And, one where I say coffee is not indigenous to a lot of the places where it’s planted. The horse or the tractor is European or Asian and being used in these other places. So, on a macro level we see this transfer of tools and then on this micro level, I think the first step is we’ll see a transfer of tools as well in the microbiological level from industries like wine and like brewing. And then that will give way to more study as to what the native results are. And even that for example, I think in 2009 the first wine strain to my knowledge that was found in a Vineyard in the US was dried and that was 60 years after this process started happening and wine. So, it’s not going to be 60 years. We’re better now, but it’s going to take time. I got I think I’m like two for three, okay.

Sarah Allen: Yeah Josh.

Josh: I have a follow-up question to that. So, you talked about saccharomyces sort of pushing out a lot of the other yeast strains. Could introducing, you maybe already answered this, but could introducing these yeast strains to environments where it’s not native potentially have a negative impact on the microflora of the farm at large or potentially push out other native yeast strains or is that not a concern?

Benoit Bertrand: You know something very interesting, a study that was produced in a California by CC Davis. I do not remember the name of the professor, a woman. She got different strains of cocoa and coffee around the world and she discovered that the main yeast that she can isolate are coming really from yeast, very common in terms of use. The majority of the yeast for the foods are coming from the human and maybe a thousand years ago, because for cooking, humans are using the yeast. And they use all this yeast are very common in the in the environment of the human.

Zachary Scott: Yes, so I think that’s Ann Dudley. I think

Benoit Bertrand: Yes, Ann Dudley.

Zachary Scott: speaking from Seattle. And yeah, she did the study. She’s a geneticist so this is really a different goal, but she was able to track that there were saccharomyces present on all of the coffee’s that she brought in from every corner of the earth. So, I think this is where I use like my dog analogy where you know, all Saccharomyces, it’s all dogs. But, you have your Chihuahuas and you German Shepherds and your Poodles and everything else in between? And so, I think here it’s really maybe the Great Dane was a better tool in this situation than the Chihuahua. So, now that Great Dane is in Nicaragua and it will crowd out that ferment but then it dies because it doesn’t have any more sugar left.

And so, there will be traces of it left that’s sporulated. But the challenge is that for it able to get traction again, it needs to grow up into a full, let’s call it a quorum of population. So, the next time that there’s a ferment it really depends how much was there to start. And that’s why when we inoculate and the amount that we inoculate and our recommendation and our dose. It’s based on making sure that we reach this magical number of population that achieves that crowding out. And so, at the base level it’s going to be present, but it certainly won’t necessarily be the king of the microbiological pyramid.

Audience 4:    The work that you have done is on Arabicas. I just want to ask whether you’ve done the same work on Robusta’s because Robusta, the mucilage breakdown is very, very difficult? So that’s one question.  The second question that I’d like to ask is now, you worked with for example, one strain of one cultivar of Arabica and you’ve done it at a particular altitude. Which yeast did you find the best between the red wine yeast or white wine or champagne? I don’t know. So, I just was wondering whether you had any particular yeast which you found to be the most effective for a particular strain of Arabica at a particular altitude?

Laurent Berthiot: Okay. I’m just going to answer about the Robusta. So, we took a load of Arabica, but we work at the same time with Robusta in Vietnam and in Mexico. So, we have all the data and all the experiment we have working on both of them.

Audience 4:    Did you find that the cup profile was better with the yeast?

Laurent Berthiot: Yeah, a lot more.

Audience 4:    Yes. You found the bitterness reducing?

Laurent Berthiot: Yeah. And you just balance the body too

Audience 4:    The acidity, did you find anything happening on the acidity?

Laurent Berthiot: The acidity is not rising a lot but as you diminished the bitterness, you can feel a better composition

Audience 4:    And working with different types of yeast. Did you find any particular yeast?

Laurent Berthiot: So, the different type of yeast, maybe Zach but

Zachary Scott: That’s like you asking me to choose between my two sons, which one I love more.

Audience 4:    I’m sure you love them for different reasons, right?

Zachary Scott: Exactly. And that’s how I think of our strains. So, imagine we have three strains for coffee, and we have 70 for wine, but and I hate to always fall back on the wine analogy, but it is much more of a mature market for this application. And so, typically what would happen is a winemaker would call me and he or she might say I have a new Syra or a new Sauvignon Blanc that my vineyards coming on. I’ve never made Syra, Sauvignon whatever it is. Never made it before. Which yeast should I use? And where we are in wine is that I won’t say well choose between my 70 children.

I have probably four Syra. There will be three strains that I would probably strongly recommend which would be related to specific types of sensory conversions for that cultivar because Syra has a unique sensory precursors. So, which strains do I already know exhibit the characteristics to express those sensory profiles? I would probably give that information to the producer and recommend that they try two or three in the first year. And then taste and oftentimes most of my clients will use one or two strains per each different type of product that they’re bringing in or even lot, so they’ll make it with two strains. They’ll split it up., they’ll taste it after, and they create a blend. And actually, one of our clients in coffee just did that very thing. They liked two aspects about the two different lots of coffee that were made with two different strains, but each one of them was a bit angular and so they created a blend between those two to create a much more rounded profile in the cup. So, that’s great.

Audience 4:  Thank you. Thank you.

Sarah Allen: I think we have time for one more question. Yeah.

Audience 5:    If someone wanted to do like a small sample trial of just one pound of coffee versus a hundred. Would it give an accurate representation of the hundred pound?

Laurent Berthiot: No.

Audience 5:    And, what’s your opinion of stainless steel versus fermenting concrete?

Laurent Berthiot: Stainless is the perfect thing but we know that it’s quite hard and quite expensive to have it. I think that the most important is to control the environment. If you can control the temperature of your tank by just covering it or maintain the good temperature of your water. You’re going to have a huge impact of your fermentation but stainless is still the best.

Zachary Scott: I think that’s actually a virtue here too, which is that the fact that the yeast is so effective at quantity. It helps to overcome also less sanitation issues. So, for example, like porous concrete, it’s very hard to clean. So, that’s one of the definite benefits is you can you can defer some capital by using a strong inoculum.

Sarah Allen: Okay, one more quick question.

Audience 6:  I did a small experiment few years ago bringing honest from Japan to Colombia. Many questions rise at the time. Basically, the first thing was we find some improvement in the cupping, but I didn’t feel like it was worth to try to bring a foreigner microorganism into the system that can create a contamination on a [55:55 inaudible] in the microflora around our farms. So, the question is related. What do you think about the environmental settings of this and do they rise any kind of ethical questions to this. Should we worry about that? I was, so I stopped doing, I didn’t find it worth to do it at the time but would like to know the impression of other people. Thank you.

Zachary Scott: Thank you. I guess the expression I was using, the glass is already broken and not just in modern times, but already going back to prehistoric times. We as humans have done exactly what you’ve said as ourselves. We are the inoculum that spread across the entire Earth and we brought things with us. We brought dogs with us, and we brought big things that we can see, and we brought plants, but we also brought this microflora already. So, Saccharomyces is already readily present.

Bring it to modern times and in Colombia every day, there is yeast that is coming for bread and for beer. And that bread and beer is then moving to each different town and each different city and each different water stream. So, we’re very connected as it relates to some of these organisms. And saccharomyces again when the reasons why we focus on it. It’s perceived as probably one of our most allied and symbiotic microorganisms in the environment because we have coexisted with it for so long and we have knowingly and unknowingly fostered its spread. So, ethically I feel okay about it. I am biased but I also think that it’s the same as the fact that we brought coffee to Columbia as well. The difference is we feel we have more control over more over larger things and that’s a very fair point too because we do have more control over larger things.

Timothy Hill: I mean from a, I don’t know if I’d be curious on their perspective. But for me, it’s more about I would be more worried about the byproduct of the actual fermentation and like what is going out from the stream, from that process as opposed to the yeast itself. But out of again I think it’s a good question and something that I’ve thought about as I’m doing these experiments. What am I introducing to the environment? But, I think controlling your waste stream and making sure that that is really intact is probably vastly more important than I think worrying about the yeast because it is already there. That’s my take.

Sarah Allen: That will conclude our panel. Thank you all so much for coming.


59:00 Outro

Heather Ward: That was Sarah Allen, Zachary Scott, Laurent Berthiot, Benoit Bertrand, Rachel Peterson, Timothy Hill, and Aida Batlle at Expo in 2018. Remember to check our show notes for a full transcript of this lecture and visit coffeeexpo.org for tickets to this year’s event.

This has been an episode of the SCA Podcast. Thank you for joining us!

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