#15 tempeh

Hello, dear listeners, and welcome to the Fermentation Cast, the podcast that demolishes fermentation fairy tales, makes starting a whole lot easier, and keeps you up to date on the latest developments in the fermentation world. By listening to our podcast, we will alleviate your fears of microbes, if you have any. And if you don't, we hope to inspire you and give you the theoretical basis to make your ferments more exciting and innovative. My name is Tessa, your future of food expert, and I co-host this show with your beloved fermentation guru, Ivana. Currently, we're exploring the world of molds. In previous episodes, we discussed the power of the genius Aspergillus. This episode focuses on another mold, that in contrast to Aspergillus, we eat as such. We are talking about the mold used for tempeh. You may not realize it, but when you eat tempeh, you're basically eating beans grown together by mycelium. This specific mold is not a family member of Aspergillus, but it has a new pretty name. Ivana? Rhizopus oligosporus. This episode will elaborate on how koji and tempeh molds differ, what gives them both a distinguished taste, how tempeh is made, and if we can use wild fermentation to make tempeh. To finish off this episode, we will also visit Bonesac, a company in the Netherlands making tempeh from traditionally Dutch bean varieties. Yum. And perhaps first, a little bit of history on tempeh, as usual, because I think it is quite common to eat tempeh here in the Netherlands due to our. sad colonial history, but other people in other countries might not know it. Yes, so tempeh originates from Indonesia, where it has been eaten since approximately the 16th century already. And nowadays, we use a starter to make tempeh, but originally, tempeh was made by wild fermentation. People boiled and packed beans in leaves of, for example, banana or hibiscus, and tempeh was probably discovered by accident, because by packing the beans in the leaves, the fungi living on the leaves actually jumped off or inoculate the beans within the pack. I like jumped off. I see this like mold. Let's go! Whee! So yeah, and then the tropical climate in Indonesia, being warm and moist, actually helped the fungi to grow the beans together. And originally, tempeh was made by black soybeans, a native plant, but tempeh can be made of any type of bean. Yeah, and I can confirm that about the tropical climate, because when I was living in Myanmar, anything that would be left outside for longer than a few hours would be fermented, so literally everything. And the fact that we know tempeh so well in the Netherlands is actually because of our so-called not-so-beautiful history, as Ivana also already mentioned. Yeah. Because Indonesia was colonized by the Netherlands for multiple centuries. And after the Second World War, Indonesia became independent, and anyone that had a link to the Dutch, either because they fought for them or because they were related, had to leave Indonesia. And these people came to the Netherlands, and they started the first tempeh production in Europe. And nowadays, Indonesian food is part of the tempeh production. And it's part of the Dutch everyday food culture. In every, or not in every, but in some traditional Dutch brown bars, you can have an Indonesian satay. Although the taste is a bit Dutchified, I still think a lot of the food culture of Indonesia is now woven into the Dutch food culture. But back to fermentation, thinking about making tempeh yourself, could we just buy banana leaves or hibiscus leaves? In, for example, a local toko and make tempeh from there? Maybe, theoretically. I wouldn't trust it, because I think these products have been treated, so probably any spores that are still on there have been removed. However, it is interesting to point out the potential of wild fermentation. So let's dive into how tempeh is made nowadays, and then compare it to how it used to be made. Yeah, perfect. So let's start with regular soybean. Tempeh. Yeah, easy. So we soak the soybeans overnight, as we always do, and then we boil the soybeans until tender but not mushy. So you need to be able to press them. They need to break down, but don't, yeah, overdo it. Yeah, they shouldn't become hummus in your hands. Exactly, exactly. Then we strain them, and we leave them to dampen. And once the beans are lukewarm, we add some vinegar. And this is actually an interesting thing. Because to my understanding, vinegar is antifungal, but we do add it in the fermentation process. Yeah, it is indeed antifungal. However, it is also antibacterial. So it helps avoid the growth of bacillus, which can cause some sliminess and off-flavors, and if you really have the wrong bacillus, even ill-making toxins. So it is antifungal, but not totally. So the vinegar kind of gives a kickstart to the tempeh mold, because it is antifungal, but not totally. So it is antifungal, but it can still cope with it, whereas it will suppress the bad bacteria. But if you would put too much vinegar, for example, the mold would also be suppressed. So you want to add to half a kilo, maybe maximum two tablespoons of vinegar. Okay, so it's all about balance, I understand. Yeah, it's a bit like with lactic acid bacteria. We add salt, other things can grow, they'll just grow a bit slower. You just want to help your friend, in this case, resuppose a bit. Cool. So we add the vinegar, and thereafter we add the spores. Then we put the beans in a Ziploc bag, and please make sure it's a thin layer, not too thick, because fungi are aerobic, and they need some oxygen to grow. And that's also why we make some holes in the Ziploc bag. Perhaps to add to that, not too thick is like maximum five centimeters thick. That's even on the thick side. That's already quite thick. Yeah, maybe more like. Three. Three, which is an inch, I believe, if you're an American. So then we ferment our tempeh, and we do so on. At 30 degrees for approximately 24 hours. And ideally, we do so in an environment that is a little bit moist for optimum growth. And then, yeah, after 24 hours, it's done. It's quite a short fermentation process. And we don't eat it raw. So after the tempeh cake is done, we slice it up and we cook it in the pan. We mostly fry it in a little bit of oil, and deep frying is also really nice for texture. And the result is crispy from the outside and chewy from the inside. Yeah. But as said, historically, tempeh was made by wild fermentation. This is controlled fermentation. Can you help us out? Yeah. So we already mentioned that the mold starter usually came from banana and hibiscus leaves. And there was another step that was added that people don't do nowadays. So now we usually soak the beans in the refrigerator to avoid any bacterial growth. But we still are adding vinegar to have an acid-starting product. You can imagine in Indonesia in the 16th century, there were no refrigerators. So during the soaking of the beans, lactic acid bacteria would start growing and acidify the beans. And these were then still boiled to kill these bacteria. I'm not sure if people actually knew that there were bacteria, but they knew it was acidic. But this eliminated the need for adding vinegar in the end. Also, lactic acid is not volatile like vinegar is, so it would remain in the beans. And probably. This resulted in a more balanced and softer taste. And it is also less antifungal. Cool. Interesting. So what we could do to reproduce this process is actually soak our beans at room temperature for lactic acid bacteria to kickstart our process. Yeah, this could be very tasty. However, when you just put them in water, you are relying on whatever is on your beans to start growing. And this can be rather unpredictable. So if you're unlucky, for example, you already have a lot of. A lot of bacillus that start growing in your water. So. And if you have a lot of bacillus, this can result in a lot of ammonia release, which is not so tasty. But we'll discuss that in a future episode. So if you want to assure that it's LAB, lactic acid bacteria that are present, maybe add a bit of juice from a lacto-ferment you made previously. Okay. And what if we just add 2% of salt as we do with lacto-fermentation? Interesting idea. I think we should try it. I'm not sure if the salt would suppress the mold after. It's not that much, but. I haven't tried it. I haven't tried it, to be honest. And another thing that can help is ferment at LAB-loving temperatures, so 25 to 30 degrees Celsius. And the more different LAB are in there, the more interesting your flavor profile. Let's try. Another question that I have is, do you know what causes the typical aftertaste of tempeh? It's a bit sour, a bit bitter, a bit. Yeah, very typical, actually. Yeah, so I was wondering, and I searched. the whole internet and my books, I could not find a conclusive answer. There can be more. multiple causes like proteins broken down or like plant compounds. But I did notice that regardless on what you grow your oligosporas on, you will always get this taste. So it must be some metabolite produced by the mold itself. I suspect it's related to the breakdown of proteins, but I'm just unsure. So if any listener out there knows, please tell us. Send us a message via Instagram, or you can also respond to this podcast just in your listening app. Amazing. I'm curious to know. And as said, in the beginning of this episode, we can make tempeh with all sorts of beans. Yeah, definitely. And this has actually been done in Indonesia for a long time already. So they used to, for example, also make tofu. And when you make tofu, you have a rest product called okara, which is kind of a mashed soybean paste. And you can ferment that. So you get actually kind of tofu tempeh. You can make it of coconut pressed cake when you're, for example, pressing the oil out. I think this is called tempeh bonkrek. You can make it of mung beans. Mung beans, et cetera. And so you can make it out of any bean. And in the Netherlands, there is a startup making tempeh from traditional Dutch beans. So kind of fusion. More on that in our interview with Bonzac later. That actually brings me to a question, because okara as well as coconut pressed cake is not a bean itself. What are the compounds in beans that we need to make tempeh? Definitely proteins and some starch. So you always want a source of carbon atoms. And these can be found in starches, carbohydrates, et cetera. So we do not, it's even wider than beans only that we can use to make tempeh. Yes, actually, I have made quite some tempeh myself. Do you want me to tell you about that? Of course. So I've made them of, well, starchy/protein rich things like quinoa, for example, that makes a very tasty, fine texture. But I also use vegetables in my fermentations. I did notice if you do pure vegetables, it is a bit tricky. So you want to add some grains to properly ferment. The thing I mentioned earlier, the soy bean tofu kind of tempeh is actually called onkom. I also made that once and I really liked the texture. It was a bit more firm and bouncy. And I've also developed a very tasty burger patty with my psyllium grains and beans myself. I'm still planning to bring that to the market at some point. So soon I'm going to Copenhagen and I will try the Poppel and Matter burger that they have over there. Poppel being from Noma and Matter. Being a separate brand to compare it to my creation. And I think you have actually tried the Poppel burger, right? Yeah, I did. I did. And it was actually really delicious, but I also tried yours and I think yours has more potential. So. Okay. Well, I'm going to take that compliment. And actually, do you also want to tell a bit about the last low food lab where we researched mycelium and there was a tempeh made of that. So that was like. Double mycelium. Of course. So indeed, in the last low food lab, we challenged our experts being chefs, product designers, scientists, et cetera, to experiment with mycelium and produced by Enuf, a Dutch based startup. And we challenged them to go beyond the meat analog because mycelium is often used in meat replacements, but we actually wanted to see the potential of mycelium beyond being an imitation of meat. And one of the things that we found was that mycelium is not an imitation of meat. So we asked our participants, Rene van der Weijden, he's the chef of Hemel aan Aarde, a really good fine dining restaurant in Utrecht. Heaven and Earth for the English speakers. Heaven and Earth. Beautiful. And he grew mycelium on mycelium by making tempeh. So his first experiment, he used solely mycelium produced by Enuf, being called Abunda, and grew tempeh spores on that. It was already really delicious. But in his second try, he used. or he mixed the mycelium with some traditional Dutch grains for texture. And the result was really amazing. And he used a glaze also made by mycelium shoyu. So it was full circle mycelium and everything. And it was really delicious. And maybe for the curious people out there, because mycelium can take many forms and shapes, but the mycelium of Abunda is actually fusarium finenatum. Yeah, we will not continue talking about that now. We will not continue talking about that now. To not make you confused. But indeed, that's for the nerdy nerds out there. Exactly. So for those new to tempeh, how would you serve tempeh? Yeah, so as said, it's most delicious if you fry it. I often use sesame oil because you can heat it up quite hot and it adds a bit of taste. And then you cook it until the outside is crispy. And I mostly use a marinade or a glaze. So either marinade. You use beforehand to soak it and a glaze you use after you fried the tofu or the tempeh, sorry. And yesterday I actually made tempeh even. And I made a glaze with shoyu and a blood orange. It was really delicious. Where was I? And of course, there are plenty more ideas. And traditionally, they often make it with ketchup manis, which is a sweet, savory sauce that is used as a glaze or a marinade. And yeah, but we haven't discussed the difference between tempeh and koji yet. Yeah, OK, so again, I'll start with first something that's the same. So they are both moles and they need oxygen. So tempeh grows quite a bit faster than koji. It's only 24 hour fermentation usually. And koji needs usually at least two days. They like similar temperatures. I have noticed tempeh grows a bit better at a slightly higher moisture content, but the taste is just anecdotal. So I don't have any scientific proof. And most of all, the taste is very different. Koji to me is more fruity and sweet, whereas tempeh has kind of a more of a bitter, savory undertone. Yeah, tempeh grows better on pure soybeans, which is a bit more difficult for amylose-loving koji. Is that because we need more starch to grow koji? Yeah, I think so. It's just what it's used to, right? Yeah, probably you could even train koji to grow perfectly fine on soybeans, but you might need a couple of runs to get it there. And tempeh, well, one of the biggest differences is in the use. So tempeh is eaten as such, whereas koji is always mixed with something else and it's mostly grown for its enzymatic power. Yes, amazing. Yeah, we have in our previous episodes, we've introduced miso and shoyu as koji-loving substances. But so you have many differences. There are many different koji-based products, such as mirin, sake, etc. Yeah, marinades. My God, the options are endless. There's a very nice book on it, actually. I want to try to get that author on our podcast one day. It's called Koji Alchemy, and it dives into the crazy world of koji. Amazing. Good goal for our next season. Another cool thing that I came to know about tempeh is that it contains vitamin B12, which is often lacking in a plant-based diet. It's something that we mostly get from animal-based protein. Yeah, so it can indeed be in tempeh. It's not always there. So I went through an article where they collected a lot of samples from different places in Indonesia, and it was found in, I think, about half of the samples or two-thirds. So the thing is, nowadays we produce in highly hygienic conditions, and you need specific bacteria that can actually produce this B12. Yeah. So the right bacteria. The right bacteria is not always in there. But Wageningen University is doing interesting research where they deliberately add propionibacterium, which is actually taken, I think, from Swiss cheese. Okay. And that produces B12, and this way they force the B12 production. So you're sure it's always in there. Okay. Actually, I came to know B12 comes only from bacteria, and normally it's found in the gut of the animal, which is often then transferred to meat or milk. And, for example, it's then naturally present also in cheese, so for vegetarians that miss B12, you can eat cheese or tempeh. Yeah. And B12 is also found in our soil. Yeah. So the bacteria, indeed, that produce the B12 can be found in the soil, and that's probably also how it came in the tempeh sometimes. And that's also why you can actually make vegan products that have B12. You don't necessarily need the animal, you need the bug. So there's another thing that I found interesting with this whole biodiversity, that I was talking about before, so you don't always find B12. Yeah. But anyway, if you produce in hyper-hygienic circumstances, the biodiversity in fermented tempeh goes down. Yeah. And while this is good to ensure food safety, it can in the end result in less diverse microbes in our diet. Yeah. And this may actually have an effect on your gut microbiome. So the authors of this specific article even go as far to claim that at the end of the day it can affect our immune system because it needs a wide variety of bacteria. So I always am a bit hesitant. I'm hesitant to just claim things, but I do think it makes sense, I guess. Yeah, we talked about it in many episodes, right? That by doing controlled fermentation, you also lose a little bit of the wild bacteria living in our environment that can be healthy, but they can also be dangerous. Exactly, yeah. Yeah. So producing for the mass kind of requires us to control the circumstances around us. Exactly, yeah. And I. Um. Yeah, so we need not only a diverse diet because of taste, but also because it's healthier for our microbiome. And another thing that I'd like to discuss is something that is a little bit less tasty, but it is the putrid smell that comes with tempeh. I have a bit of a hard time with this word. We typed it on Google Translate, it's putrid. Putrid. This putrid smell. Putrid. Do you know where it comes from? Yeah, so the putrid smell comes from the mold breaking down protein. And when it breaks down protein, it releases ammonia, which you may know from the countryside when the farmers are spreading manure. And it's quite stinky. And it also causes an increase in the pH. So that's another good reason to start with acidic beans because otherwise you would have super putrid beans because the acid actually, it neutralizes some of this ammonia that is produced. Yeah. So the older the tempeh, the more protein is broken down and the more putrid it becomes. So personally, I prefer a fresher, tastier tempeh. Tastier from. It's subjective from your perspective. From your putridity, yeah. Okay. Last question for today is sometimes you have tempeh with little black spots. How come? Yeah. Tempeh spores are black. So if you ferment a bit too long, or when there's a lot of oxygen and the tempeh is very happy and thinks like, I'm going to reproduce, this can happen next to the holes. So it's going to especially happen where there's a lot of oxygen. This is where the tempeh is very happy. So it just starts producing some babies and the babies are black. They are perfectly edible though, but they might be a bit putrid. Well, sounds delicious. Okay. Let's go. To Sebastiaan and learn more about making tempeh from original Dutch bean varieties and how these bean varieties actually influence our flavor of the tempeh, we will visit Bonesaak. They're almost our neighbors. Their production site is in Amsterdam-Oost and we will hear more about Sebastiaan. Tasty. Welcome for visiting Sebastiaan today in Culemborg at Bonesaak. And yeah, I have Sebastiaan next to me. So, well, can you tell me something about yourself and about Bonesaak and how you started this wonderful company? Yeah, thanks for, well, happy that you're here. So with Bonesaak we make tempeh, so I'm a tempeh maker, let's say, who's been active in mostly the protein transition in Holland for about 10 years now, earlier focusing on mainly Dutch soy. Production and now really on really tempeh from anything but soy, basically. And we do that with a small factory in Culemborg, which we've launched about one and a half years ago through a crowdfunding. And why not using soy anymore? Well, really, I have nothing against soy tempeh. Actually, it's really nice. Definitely. If you make a fresh soy tempeh yourselves, please do so. Um, but about four years ago, I started making soy tempeh myself. I started making soy tempeh myself. Four years ago, a foundation, Slow Food, Slow Food Netherlands specifically, they launched a challenge, so to say, a biodiversity challenge, how to get species, Dutch food species that were about to go extinct back on the menu. And to our surprise, me and a couple of other tempeh makers who made tempeh as a hobby in their free time. By that time, only from soy found out that among those species to go extinct were 12 different Dutch bean races. So one of our ideas was what if we could turn those into tempeh, knowing that beans are a declining market in the Netherlands, shamefully so. But tempeh is actually a growing market. So what if we could turn these beans into Dutch heritage tempeh? Wow. And how did tempeh actually got to you? Because it's not a usual Dutch product. It's not. But if you're working with Dutch soybeans, which I had been doing at that point five years ago for some time, then tempeh is one of the most logical. So I made milk or soy drink from it. We made yogurts. And at some point we started working on tempeh. And I really feel that definitely working with chefs, tempeh is a vehicle in the protein transition, seeing that chefs are quite reliable. And I really feel that tempeh is a vehicle in the protein transition, seeing that chefs are quite reliable. to work with many of the meat alternatives on the market they want a more well a less processed food so to say which i feel tempeh can really fill that void and fermentation is hot and happening with chefs right big trend okay um so bonzac is making tempeh with dutch heritage beans you said there's 12 different sorts of beans that you use to make tempeh with so there's 12 beans at the point which we started it should be still be around 12 there's 12 beans in a list called the arc of tastes which is basically a list of foods that are rare in holland and slow food slow food wants to preserve them and that has a biodiversity mission as well as a culinary mission um we started working testing about 10 of those and we found out about seven of those work really well for making tempeh so at this point we have three different beans actually in production and we're working on two more so we're launching two more this summer and what makes a bean better or worse suitable for making tempeh size um so the bigger it is the harder it is because you get more air gaps to for the mycelium to to to fill those voids uh the thickness of the skin so if a bean has a really thick skin like like some peas so not technically bean but a legume peas uh often have a bigger skin one of the peas we work with uh the grey pea has a really thick skin so the starter uh the fungus has a hard time getting through the nutrients very clear i guess can you um because we're we're here physically but the listener is not here physically can you uh show us around like talk us through what do we see here in your production site definitely yeah so so on your left you see basically all the the bags of beans that come here directly from the farmers what do you see now is about um 800 to a thousand kilos uh which would last at least half a year um five different kinds of beans so the three that we have out now and two that we're still working on are releasing this summer uh then on if we go out the door and to the right you will see the production hall which is kind of a a food safe hall where we and six other companies that that we share so when you only use it like three to five days a month uh where we produce the tempeh so there we we soak it we cook it boil it i mean the beans and then we mix the beans with the starter and we package it and then at the end of that hall you see our fermentation rooms which are basically two old freezers that we upgraded to fermentation rooms nice fermentation cast okay wonderful um are you doing this are you doing this alone or who is on your site we are doing this with a lot of people so we started out with the five of us four years ago but uh the making of it turned out to be quite uh time fulfilling and starting a business uh quite as kind of a stressful time stressful event you could say uh next next to the lives we had so it quite early on in the process about two people left uh then two others came in and now we're doing it with a team that's also running a soft drink brand right here in cumber so they're helping us in production logistics which is really great so we can use their experience so now we have a team of about five yeah wonderful and uh the the soft ring brand is also a big part of the team so we have a team of about five yeah it's also bunker right also in all in food transition upgrading waste streams and vegetables and fruits that otherwise never come to market wonderful company um but back to different beans and different flavors because we're curious how does a particular bean influence the flavor of the tempeh so that was at the point where we found out the difference in flavor between the beans uh that was for us a starting point like we really have to go beyond experimenting and just start a company start at start being tempeh makers and selling the tempeh because we were shocked by the the difference in flavors once you ferment these beans so if you have a a freeze of outbound so a fish and forest bean and a crooked bean a comeback the difference once you just soak it cook it it's not that huge but once you ferment it you really taste the difference flavors that you wouldn't find if you only eat it after boiling it um so so to say a a a crooked bean has kind of a a funky aftertaste a bit salty the grape pea really gets sweeter uh fresh and forced bean gets really creamy when you turn it into a tempeh so if you look at these five beans you really get five different flavors five different tempes and really every chef is really specific about which one they want no chef ever said to us give me any tempeh they always go for one specifically one they really like and do you know what particular um components of the bean actually make that the flavor differs i don't honestly uh could be the starches could be could be a lot of different things so actually ivana is pointing out her hand here so maybe our fermentation guru knows the answer always good to be present in the tempeh factory so i'm not 100 sure but i suspect it might be the kokumi compounds released by our tempeh mold and kokumi compounds are compounds usually peptides that you don't necessarily taste themselves but they function kind of as volume bottoms that crank up the volume of other flavors therefore making dishes more wholesome more savory more delicious so i suspect your recipes might be doing that in your tempeh thank you ivana um yeah so um going back to these different beans and uh you deciding which beans work better or worse it was size but probably also flavor which were more interesting or less interesting could you explain us what is your favorite and maybe also an experiment that didn't really work out or the tempeh that didn't really turned out to be so delicious as you expected it to be yeah so for me your favorite would definitely be the crooked bean because it's more funky it really has that fermentation flavor what we do notice that if you're not targeting fine dining but more the average restaurant you want to go for a a softer tempeh which is less less distinct flavor a really neutral flavor so which gets closer to soy tempeh because people are used to that um and are not we find out not so much used to the fermentation taste of really funky tempeh um but for me personally uh so the crooked bean tempeh works really well um for chefs we see that the gray pea tempeh works really well because of the thickness of its skin it has a lot of bite so you're really surprised when you eat it that you're actually eating a tempeh because it's so different from bean or soy tempeh um what doesn't work well uh it's not so much the bean per se uh but it's the fact that you're still baking beans if you're cooking tempeh and people definitely in holland see it as a meat replacer so often they put in just a little touch of oil and then put it in a frying pan that doesn't work well because beans they need some kind of moist so either you put it in a lot of oil or you steam it but just putting it in the oven or in a frying pan you basically get dry beans and we all know how dry beans taste so that's really a thing for us to work on with dutch consumers so indeed listeners listen carefully please use a lot of oil or indeed steam your tempeh because otherwise you will not get the result you wish for um what's your favorite recipe with tempeh do you have any like funky specials that you would serve your guests when they come so then again i would go back to the crooked bean and that's the recipe that's also on our website it has a bit of a funky salty taste so it works well if instead of if you put it together with a mash of potatoes of some kind and really kind of see vegetables um you could see it as a fish alternative we don't necessarily see it that way but we often get the question so what would be a good meat or fish alternative and we say the so we often bake that we call it a a baked on the skin crooked bean and we put that together with some sea vegetables some mash and you have a really good dinner wonderful i'm excited to try this out so we will go and have some tempeh together but thank you for listening and thank you sebastian for having us in your factory and i hope we have you all trying tempeh from dutch origin beans from now on so if you want to find bonzac's products you can go to bonzac.nl unfortunately till today we're only servicing dutch clients but we have plans going abroad right germany germany is first so if you're listening from germany hold your horses we will get there thank you sebastian once again and have a good evening so thank you sebastian for having us and for all the extra information on how bean varieties influence the flavor of our tempeh this episode was all about the traditional indonesian bean cake called tempeh we introduce you to the traditional and modern ways of making the product and there we've discussed controlled versus wild fermentation we briefly introduced the smell and flavor of tempeh and how it comes to life there was some inspiration on how to cook or fry tempeh and i guess that's enough for for now we hope to uh yeah set you on to buying and trying some tempeh and next up is an introduction to our last category of our fermentation tree called bacillus so we hope to see you there Thank you.