Ep 21 - Sensory Part 2 - Key Flavours & Taints - Jethro Duarte-Holman

In part 2 we deep dive into 6 essential flavours and taints commonly found in beer. After this episode, you will be able to:

- Know what they are
- How to describe them
- Where they originate from
- How to remove them (if desired)

Key flavours and taints covered:

🧀 Isovaleric 
🗑️ Mercaptan 
🧈 Diacetyl
🖌️ Acetaldehyde 
🩹 Phenolic 4EP  (Honourable mention of 4VG)
👶 Butyric Acid 

00:00 Introduction and Overview
00:49 Brewing Trade Advertisement
01:55 Introduction to Sensory with Jethro Holman
02:26 Discussing Common Flavors and Taints
03:30 Isovaleric Acid in Beer
08:12 Understanding Macaptain
17:59 Diacetyl: The Buttery Off-Flavour
26:59 Avoiding Apple Descriptions in Beer Tasting
27:54 Understanding Acetaldehyde in Beer
29:52 The Impact of Oxygen on Beer Flavour
32:49 Trans-2-Nonenal: The Papery Off-Flavour
37:18 Butyric Acid: The Baby Sick Flavor
42:06 Phenolics in Beer: Good vs. Bad
45:51 The Importance of Sensory Training
46:52 Common Mistakes in Sensory Evaluation
49:15 Final Thoughts and Recommendations


💰 Brewing Trade

📧 jethro@brewersselect.co.uk

🔗 Chris' LinkedIn

Transcript

0:12

Hello everyone and welcome to the latest episode of the Modern Brewer Podcast with me, your host, Chris Lewington. This is part two of our deep dive into Sensory. in this episode, we're going to talk through seven different flavors and taints commonly found in beer. What How to describe them and where they originate from. Listening to part one isn't actually necessarily essential, but it is highly recommended as it will help you develop methods of actually catching these flavors and taints, which is pretty essential to be honest. But before we get into it, I'd like to take a moment to talk about brewing trade. Brewing trade is revolutionizing the way UK and EU brewers are buying hops. Instead of paying full price for hops brewing trade, customers can purchase hops directly from other breweries. Surplus requirements meaning buyers get much better prices with exactly the same quality hops as purchasing from the spot market. Saving on an average of 25 percent of their hot costs, Brewing Trade users are using their savings to purchase newer lab equipment, saving up for new fermenters and investing in staff training without having to spend any new cash. Shipping on Brewing Trade is cheaper than the spot market purchases and the minimum order quantity is often just five kilos. Be a part of the hop revolution and set up your free brewing trade account on www. brewingtrade. com or check out the show notes for a quick access link. So let's get straight into part two on sensory with the amazing Jethro Holman. All right, welcome back everyone. Jethro is with me again. Oh, sorry. Uh, the long pause was on purpose. I was completely looking out the window. I thought you were doing a bit. I didn't realise I was being introduced again. So Jethro is with us. Oh, hey, what's up? How's it going? Really nice to be here. Uh, I'm not even gonna edit that out. Yeah. So we're on the next episode. If you haven't listened to the first one, please go back and listen to it. We set the scene on everything you need to know about Sensory as a whole and in this episode, we're kind of gonna go over some I don't know five six a few key flavors That you can detect in sensory Uh what they are how to describe them and where do they originate from and what you can do if you Find it and hit that big panic button and more I think what it could in terms of like and These are all things that occur and and that they become conversation pieces and action points You know, like it's not just a game to smell them. Like this is real world. Yeah, yeah, yeah, yeah. It's not like, oh, cool, yeah, I got uric acid. That's awesome. Oh, oh man, you got 90%. Um, yeah. Um, so yeah, I mean, I guess. Do you want to just fire some over? I think we should just start firing some over. You know, I've already mentioned Maybe that's why I was looking out the window, I was like, Oh, I'm about to be put on the spot. Yeah. I mean, yeah. I think these are like pretty common ones. I say let's start with some, maybe some more hot based ones. Like, what's isovaleric and If you've got isovaleric, then you you want to ring up probably your hop supplier. so not me, obviously. Unless their name is Geoffroy and they work for Locker I only sell the highest quality hops from Oregon. Come on. Um, no, uh, Isovaleric is, is produced, like, by hop breakdown, basically. So, uh, poor storage or poor cold storage of your hops when you've got them. And it can also occur within your beer as well, as your beer ages. but I would say it's probably you know, you're buying some nice Cheesy leaf hops or something and leaves are awesome I'm, not saying that but it tends to happen a little bit more just because of of Uh, you know, the way they're stored or whatever. You can also get isovaleric from, from some wild yeasts as well. But, that's, that's less common. isovaleric, the, just to quickly talk about what that would be. the common descriptor is, is parmesan cheese. or sweaty gym socks. which seems mad, but you, you, you do get it in beers. And it's not always a bad thing. Like, I've had some really great beers. Really strong British IPAs, like proper COR and wire IPAs. and they smoked cheese. And I've been like this fantastic. The bitterness absolutely free the roof. I'm not saying I drink those beards regularly. but iso IC isn't, always a bad thing, but generally it means that you've got a poor quality hops, old hops have not been stored properly or sometimes your do can affect the way you, you're storing your beer and your hops are aging, you know, faster. Mm-Hmm. So, yeah, I would say, you know, kind of things to do, contact your, your hop supplier. But I would also say that, that something like hop characteristics that come from aged beer are another reason, you know, previously we were talking about shelf life testing. That's the kind of thing I would track is, is thinking about your negative hop attributes that come over time and seeing how quickly they occur in, in said brand. yeah, I used to make a 6. 4 percent IPA. and that it, you could see it so quickly. and it just in that particular beer style, whereas our 4. 2 percent session IPA, that may have had the same suppliers hop in it, was not as prevalent, you know, as quickly. I did a shelf life test once on, on a, on a, we, we brewed it three batches of the same beer style, and they had different, you know, The actual trial was about different hot products and the way they came. but part of the trial was that we tasted the same beer every single week, blind, refrigerated and ambient. So we had the same batch, same batches in the fridge, same batches ambient, and then we taste them in panel every single week blind, so the tasters never knew what was happening. So we had real, like, real world. Tracking of like line data, and seeing negative hop attributes like isoalleric appear on ambient shells compared to the refrigerators. Unreal. You know, we talk about it and we kind of laugh like, oh yeah, keep it cold. but yeah, something like that is going to come over time. But, yeah. And if you're selling in supermarkets, Which is quite common, that's a big one, right? Because I only see many fridges in those supermarkets where the beer's stored. Or they're open and there's no door on them. Which is insane, by the way, fridges. I doubt it, yeah. It should be illegal to have fridges without doors on them. Yeah, it is actually mad, isn't it? Yeah, yeah. cool. Yeah, I mean, I suppose that's it really. I assume the lyrics are probably quite a quick one, that's just like, It's more hops, so there's less investigation needed, I think. Yeah, it's a pretty simple one to start with. I think I would generally would be Yeah, as you said, I think It's one thing I really want to probably get away with, or take away from this, is that not every single thing is an off flavour. Mmm. As you said, some parts and flavours, I think We're definitely going to go diastolic on this, but You know, that's by a lot of craft brewers are considered a you know an off flavor and it's like Oh, I don't know. I'm on diastole my beer, but actually some people gen it's a beer style It's a bit of flavor and it's generally in there for a reason So I think sometimes when you smell I think it's important you're assessing other people's beer that you're not always Holding it to the same standards you hold your own very much. So I find I really get annoyed with People who are overly critical. I know that sounds stupid because the whole job is to be critical, but will Like In my past career I spent so long assessing beers, or tasting beers, that I for a little while got lost and I stopped drinking beers. and there's, there are many positive attributes to be found. and, yeah, we're so off topic already, I love that. like, and it's important to, you know, to look for positives as well and to be tactful with brewers. Do you know what I mean? Tell them if they've got something really wrong but don't sit there and bollock them all the time for it. Like, like, yeah. Let's go on. We'll talk about it. So whilst we keep on, maybe the, the hop line to some extent. What about Macaptain? Macaptain. Macaptain. Macaptain. Macaptain. there's all sorts of names, but we'll, we'll say McCaptain is how we used to train on it. it comes, hops is one of the ways it comes from, it's a file. So, you're going to get it in, hops that have lots of files. I'm not going to discuss that, what files are on this podcast, because we don't have anywhere near enough time for that. but, it, just quickly, before we talk about McCaptain and hops, it, it can also come from a second autolysis aroma as well, so if you are, like, leaving your beer, sat on it, sat on your yeast for too long, not getting it off, there is an aroma that can come, but, just quickly before we talk about where Macaptain comes from, the common flavour descriptor for it is, bin juice, which is really pleasant, so the, the aroma when you, lift your bin bag up before you take it to the bin, which is not pleasant, and, It's, it's, it's something that once you've trained on this and you've had it at a high level, you get to know the aroma properly and then you lower down your threshold of it. You start to smell it on many different things. Like there are some particularly high phial, hops that are really popular. that just by nature of the way they're used, you often get macaptan on. and I think Some bits have been spoiled for me on learning this aroma once I gave it a negative connotation in my mind That's also important when you're thinking about flavors is you're giving these things Negative names often i'm describing something as bean juice when actually what i'm describing is somebody's Favorite west coast IPA. Do you know what I mean? And they never even thought about bean juice But if I was to tell them then I might have spoiled it in their mind a little bit but my captain when it comes to hops you're gonna get from some Higher fire hops. I'm just going to name a few, but like net, Nelson, Citra, I don't know, like mosaics is quite a lot, but that's not to say it's bad, but you, you'll find it in the way you use it. So maybe if you're, you're, I'd experiment once you kind of learn what my captain, the aroma is, if you're trying to do something crazy with bio transformation, or if you're like doing different temperatures, when you're dry hopping and whatnot, you might find that it becomes more present in your product. Does that make sense? Yeah. Am I right the, the saying? Have you, have you, have you encountered my captain in your brilliant life? Oh, yeah. Yeah. Okay. Yeah. Yeah. I mean, I'd say it's a, it's been a, one of those compounds that the, been a scro in my career. I really, really, really struggled with this one. This is, this is one of those things like, you know, there's, I've say ignorance is bliss. I really do genuinely believe in the captain. Ignorance might be bliss. It's, It's a hefty compound to get your head around, and it's, once it's in, it's very difficult to get out. Yeah, yeah. And, yeah, in fact, I would go as far as to say it's extremely difficult to get out. And the origins are also not easy to, I mean, the oesophthalmosis, fairly easy, but It also depends a lot on your dry hopping schedule and how you dry hop. So if you're using high mechanical action to dry hop, uh, you know, I think we used a hop nick and no one's seen those before. It has a macerator on the pump and it resets the whole bit is actually churning everything up causes high yeast autolysis. So then you stuck with this, like now you've got this yeast autolysis problem and you haven't got long. So then how long do you leave the hops on for? If you're leaving the hops on. With yeast for, I don't know, over 72 hours, I think we were finding big problems. And this is why this, this compound has always been like, tough to get your head around, I think. from, from my perspective. We did manage to get, effectively get it out of there, but we had it on Sunday. I've had it, the, the brewery that used it. We're talking about I have had it on so many of their beers. I actually stopped drinking their beer for the three. Yeah Yeah, yeah. Yeah. Yeah, it's that's obviously even popular so people don't mind. I I think and I want to ask you like How do you assess? To get my captain because For me if i'm at a pub, for example I'll get a beer that's got a lot of my captain on and the first Two sips, I'm having a great time. I think this beer is super hoppy, I get it to my nose first and I'm like, Oh yeah, here we go, it's got loads of aroma. And by about sip three, I'm like, Woah, I'm picking together with my captain. By the end of the pint, I can't, I almost don't want to finish it. And I've never had a compound that goes so from like, I don't know if it's because I'm not tuned in at the time or something, it always catches me when I'm out. I'm like, oh this is amazing, great beer, and then I'll be like, ooh, that's getting worse, and ooh, that's getting worse. So say, like, a hop that will give you a lot of maccaptain, I'm just going to say Citra because it's in every beer in the world ever, but, and it's a beautiful hop, and it's going to have so many things hitting you at the same time with your first nose in moment, your first enjoyment moment. And then you're going to sit there for a while and it's going to warm up a little bit in the glass and the aroma is going to prevail through and then you'll pick up a little bit and then once you've twigged you're like oh my goodness. and it doesn't matter all those beautiful citrus notes there that you're just, your brain tunes in on what's there. on that, so. Yeah, a good solution if you find you're getting Mecaptain in your beers a lot once you know what you're looking for is just as you were talking Chris You consider your your dry hopping schedule or just how you're doing it on your processes And also it's a really good opportunity to look around and try different hops Yeah, yeah, it's often hop variety specific that you're gonna get more of it, so. Even to the sense, bat per batch? So, bat, if you've got, let's say, we'll take Citra as the example, if you've got batch A, B, and C. Yeah. Are you, you're gonna get more in A, less in B, and medium in C, for example? Yeah, I mean, the lot number, maybe, so it, it might be something worth, if you can chat to your hot supplier, say you're getting this problem, say that you think it might be your, your I'm not going to say particular brand because that's a certain supplier or any supplier say this hop that i'm using Has i keep finding this mecaptan i've assessed the way i i'm handling my beer can I have another lot? and try it with a new lot and see what happens and try try a different crop here, you know Like i've been using crop here 22 have a little go with some 21 see what happens Yeah, and you may find that that the the issue's gone. So, it's You Hassle your supplier Always there's a good episode on that. Am I right? Yeah, you're not wrong Yeah, we go. The knowledge is that Andy from element a good friend of mine yeah, we people under use us as suppliers like knock on our doors and don't complain because they're nice people But we're there to provide you with with yeah Resources and make changes and and help you make better beer. So Yeah. If you're getting the captain sit, sit down with your mechanical processes first, but also think about your ingredients. There was also a really good MBA podcast on my captain, with dogfish head, so yeah, again, as I said, we had this, we had this problem and it landed on my lap. And let me tell you, I probably read every resource that was available on the captain. and yeah, they linked theirs to Whirlpool trip. Okay. for people who listen in the states, I realize you call it Trobe, which was a real eye opener, ear opener for me. I was like, the hell is Trobe. People called Troub tro. Anyway, it sounds like something from Lord of the Ring . True man. Yeah. so, and, and they were, they were linking it to the Whirlpool Troub being brought over. So what they were doing is in the first six, 12, or 24 hours of fermentation, they were dropping out that cold break that sits at the bottom of the fermentor, and they found it really. dropped their perceived levels of the captain, which is what I found really interesting. It didn't work for me in my case. we also had fermentations that were ripping, so, you know, 24 hours later you were just dumping beer at that point, so. yeah, I think mechanical action and doing time on hops I think is a really, a good way of assessing, my captain. Number one, it's, It's a, it's a curse, that one. It's a really, really, and I said once it's in, it's, it's kind of in. There was a brewery there, early on in my craft beer life. a brewery from South East London that I, I wore the hat. I was that much of a fan. and then I started to realise that it was in every single one of their beers. And I was like, fuck, I can't wear the hat anymore. and they were my neighbour. Yeah, that, yeah, exactly. But there's some people who, I mean, I've been at a pub with you, will have the same pint that I am having. And there was actually one, from the brew that I worked at, and I was like, oh my god, it's got this, it's got macaque in it, and I was stressing about it, obviously, because, I was, yeah. And they were like, oh, this is a great pint, they're having a great, like, this is a delicious pint of beer. And actually, on a lot of double IPAs, for example, I think it's quite common, The more you're getting the hops in, the more you're It's quite common! I'd always say Your Russian roulette's got more bullets in the chamber. What a lovely way of putting it. Yeah, I think that's a, yeah, it's a, it's a really good compound, a captain to, to both find and then, eradicate if that, if podcasts about, love that Master of the Earth podcast. Yeah, it's, it is, it's the best. second best. Second best. It's the best. I, one thing about my captain, isn't just, isn't the actual compound itself in gas? Yeah, they use it in natural gas, so they put it in natural gas. Odourless gas. Yeah. So that you can smell it. So that smell is Yeah. So, yeah, the, just for safety. Yeah. Because some natural gases are odourless, so they add odour. cause yeah, the fresh odour is like, really. you're now going to start asking me about natural gas and all that stuff. Yay! But I do know that. Modern gas engineer. Yeah, yeah. New podcast coming out. God, yeah. Can't wait to be on that one. alright, so let's move to the, to one of the big ones. diacetyl. what is it? How do you describe it? Okay. It cringes me out talking about Darcel so much because it's like, we have to because it's so important and it happens in our beers and we talk about it all the time. and it's the first one that everyone wants to talk about when we talk about sensory because it's so spoken about. I mean, I will go over it really like, you know, the, the, the The flavor descriptors are going to be, like butterscotch or butter popcorn, margarine or fake dairy products, vape pens. and, and it also has a mouthfeel as well, which people often overlook. So if you've got, and sometimes workers, Dastal does have some confusions with other, just natural processes within beer or malt profiles. but Dastal has, particularly at higher levels, has like a really, I call it a slick mouthfeel. so if you're tasting some Dastal and you rub your tongue along the roof of your mouth once you've swallowed, it's kind of oily. Ironically, because it's like buttery. but yeah, it has a slick mouthful. So if you're really looking for it, that's like part of the test. Which is tough, because when you do D test assessments, you normally are sharing. So you don't really want to all be drinking out of the same, cup. but we'll leave you to do that. so yeah, that would be, the descriptor. It's produced by yeast during fermentation. It's not a bad thing at all. Like, when it's Prevalent when it's, when it's not prevalent. When it's needed, when it's there. Yeah. it's a bad thing in, in finished product, but it's gonna exist during, the process. and a good brewer has their, their rest afterwards or whatever, and they have time to, to get rid of it. There's also like enzyme products you can buy now, for example, like A-L-D-C-A-L-D-C, A LDC, which will, stop it from being there anyway. so a lot of people using those. If you wanna do that, realistically, you, you. You don't need them need to use them, but some people do and that still can also be produced with some like lactic acid producing bacteria So it's not only it doesn't only come about and during or like at the end of fermentation It can come from spoilage in impact product and that's rather yeah I also can come with the time the times that I actually tend to see it the most on the market now You particularly because I tend to spend time with people brewing hoppier beers, it can sit alongside your dry hop, sorry, hopcreep, because that's, that's another stage of fermentation that you're not getting your, your rest on. So basically, cause it's in a can at that point. so sometimes when you've got breweries that are struggling with hopcreep, they're also having dastoor no beer in the end, so it's like a double whammy for here. this is a minor point. So in which case. Consider trying to fix that maybe think about other hot products cjx or something. I don't know. Yeah, I'll tell you I'll tell you a story about How I learned about hot creep and diacetyl the hard way So we were doing the exact sensory training you were talking about and it was day two, so Everyone was like, you know well involved, you know thinking especially me thinking we're really good at it and We go out the room, if you remember from the first episode, you get like, I don't remember, like 8 10 samples and there's a reference sample and it's usually, you know, your beer at that time and we went out the room, we did the compounds, we went out the room Oh no, we did the, we came in for the second round and everyone picks up the reference beer and goes puts their hand up, excuse me, to the person who's running the sensory I, you've clearly mixed this up Like this sample is, been spiked with diacetyl. I, I think you've accidentally put it as the reference sample and they're like, no, no, no, no. And just like, no, no, no, no. Trust me. Smell it. They're like, I've smelled it. And you're like that horror of realization moment of, oh my God. We, you know, we had, we used to assess beer before it went out, but you know, just rarely did it when it was out. And, Dry hop creep is, I guess anyone who's hop, hopping beer or dry hopping beer has probably experienced it in some capacity. And what I later, or very quickly learned after that session was, dry hop creep's really important for diacetyl production. So when, when you get that creep and you get that extra fermentation, you get a big spike in alpha recital actate, which is the precursor for, diacetyl and yeast would normally metabolize that. Turn it into acetal acetone and that would be the one you can't smell and When you're, when you've dry hopped your nitrogen levels are super low in your yeast, it's really not healthy It's not having a great time. It doesn't want to be fermenting this so it takes an extremely long time To start to actually metabolize this and you have alpha acetyl lactate is not, you can't smell it So you smell it going, you pass it going into you know, BBT or whatever and it gets canned And that will then turn into acetyl and there's no yeast to metabolize it. and you'll just be stuck with pretty severe levels of acetyl in your beer if you don't want it there. Which, we didn't at the time. So, we learned that the hard way. and it was a real eye opener. And again, it's one of those reasons why sensory is so important. Training and sensory on a whole is so important and measuring throughout, sensory throughout the process and after the process. Because everything can be rosy when you're putting it into the can and you think this is going to be the best beer ever. And then by the time, you know, one month, three months, as Jethro is saying, you can end up with something you didn't anticipate. Because at the time you couldn't, there was no way of detecting that through the sensory methods you were doing. That's why I always recommend for anyone I speak to now to do that forced VDK test or forced diastole test, that's what we called it, before you, if you, especially if you ever see dry hop creep, you have to be doing those because it's the only way of detecting the alpha acetalytic, sort of levels. And again, if you have that problem, just, you can, there's enzymes to sort this out these days. Although they tend to only work for the upstream. Okay. Yeah, we, they do help, but you have to use them quite a lot more than they, because it's, you, the pH is low. It's not the perfect environment for this. And there's no way it was designed to be, but also at the same time, once it's, once the yeast kind of settles out there, the LDC goes with it. So if you put it in, let's say the workstream, you actually, it won't be as effective in the dry hopping afterwards because now it's no longer in the, the enzyme doesn't exist as much in the, in the beer or the work you put it in. So it's yeah, that's that's some dry hot creeps are really yeah a really good one and For anyone, I will actually link in the show notes how to do a VDK test, because it's, anyone can do it. It doesn't actually require any lab equipment, just a way of heating it up. Yeah, just not in the microwave. it literally, the microwave will flash it off. Like, if ever you see people do it, it's completely pointless. That's, I, I mean, I haven't ever done that, but I didn't know that you shouldn't do that. Yeah, you shouldn't do it. I've seen people tell me they're doing it in the microwave, and I'm like, what the fuck? yeah, so your hot plate and a stirrer, or Site between 16 and 70 degrees C so yeah, for like 10 minutes. Yeah, 10 minutes. So I, I always tended to do a little bit longer just so that the sample could heat up, while it was in the hot water. But yeah, we used to measure the liquid when it was hit. Yeah, exactly. A certain temperature, 10 minutes of that, or 20 minutes or 30. I mean, I don't think you can really, yeah, I actually, in, in the brewery we did, I like spent, I literally just sat there with ome numerous times and worked out how long it took to, for the li for the liquid to heat up in whatever our container was, which is a glass jar. And then I added that onto the 10 minutes I told everybody came in to do it for 12 and a half minutes or whatever but just because so they didn't have to sit and measure it every time but yeah, there's that's a million sites that have got the method of it online. Yeah Yeah, i'll link one just for everyone. i'll bet in link one. But yeah, I think if If let's say you don't dry hopping or something and you're still getting diastole and you don't want it there There's I mean there's other areas it could come from. You I think often fan is linked to, diastole production. I generally think your fan is probably going to be a cane and all malt beers. So when you start using adjuncts, that you might, you, you should start looking at your COA, for example, to see how much you're going to get. I'm working that way. again, there's a podcast on that, on the malt COA. And I'll just, I'll say quickly, it's not always a bad thing. It's not at all. Yeah. You mentioned that earlier when you said that. We started talking about something else, you know, check pills and whatnot, I've got it in there. Yeah. And also, we all love butter popcorn, so, it's like, again, it's setting. It's that clue. It's set and setting. But yeah, in most beer styles, get out of here. Yeah. Yeah, and it's, it can be pretty, yeah. It can be pretty off putting to some people. Mm. It's the mouthfeel that gets me, to be honest. Alright, so that's the, diastole. what one do you want to do next? Pick one, Geoffrey. Fire, fire some out, buddy. well we mentioned it in the previous part, or the first half of this part, how are we doing, acetaldehyde, do you want to talk about that? Yeah, I've got a lot of acetaldehyde, I've wrongly labelled it as DMS, it's emulsion, I think that's the one that you get for emulsion paint. So my, our descriptor for acetaldehyde would be emulsion based paint, or my other one would be the, the scraping of a pumpkin seed. which is quite a distinctive smell, actually, if you've ever scraped a pumpkin. The one I would say that I would try and ask people to avoid is saying green apples. Interesting, because that's the one that gets, yeah, yeah. People say, oh, that smells like green apples all the time. There's a few other different, flavors within beer that are, you know, You know, apple like. And who's going to sit here and talk about the differences between a granny smith, a jazz apple, and a, you know, raven. I'm actually a massive apple nerd, so. I actually probably could. We'll talk about that later. What's the really dark red apple called? Red delicious. I don't know, that was a test you passed. but I tend to try and lean people away from talking about apples. When they're describing, beer flavours, because apples are so varied. and we'll get some things in our heads. So, if we're talking about acetaldehyde, I tend to go for emulsion based paint. so, this one, when you get it in beer, is going to come from quite a long sniff. So, a large inhale. So, whereas we were talking earlier about, things like DMS that come from quite far away, and you need to kind of be smelling fresh air beer, fresh air beer, acetaldehyde. That's what you want to get here. Your nose right in, you're going to get that emulsion based pain. It also has a, like a drying, astringent mouthfeel as well. which in higher levels can be quite unpleasant, to be honest. although I will say at a small level, if you have a little bit of acetaldehyde It's often it makes you the little puckering of your mouth. Let's say makes it you want to drink more so you have another sip and it's even worse and you go again and then yeah Suddenly you drank your whole pint and then the barman thinks that you thought it was delicious And and and because it'll often sit alongside beers. Maybe that are quite hoppy as well and it's like oh, this is just so bitter Yeah, yeah, but yeah, it's emotion based pain. tends to be uh The the The descriptor, I try and say, so it's produced, by yeast during FNL production. So it's not, it's going to be there at points, you just kind of don't want it there at the end of fermentation. So that's why I recommend if, if you're doing your D test, it's a good time that you're going to be, just be aware of acetaldehyde as well. A few times when we had it in the brewery, we would be assessing, for, for dacetal and in our not heated sample on our D test. We would also remark if there was acetaldehyde, at any point, and if you have got it to the point where you need to get, or, you know, towards the end of fermentation, I'd say you'll look into carousing if you need to, but it's not essential. or not, not essential, but it's quite a big move to make. you, you talk about it a bit more as the Yeah, Rausen and Krausen. That you can solve just about every cellular problem with Rausen and Krausen. Yeah, yeah. Go on, go on. yeah, I, for me, Asteroide 1, I, I really It clicked into my head. It was, if you ever go into a pub, it's probably definitely in the countryside. Yeah. And on like a Wednesday and the cask has been on since Saturday and it's just They pour you the pint. I mean, you should never order one on a Wednesday. That's like the golden rule. But you order one, you get it. And it just stinks of emulsion paint. And it's because you get a lot of oxygen in pack as well. Right. That's going to be a, yeah, that's the second time it comes around. Yeah. The second, yeah, I, it, it kind of ruined cask bith for me for a bit. Cause I would be like, if I could smell it, cause sometimes you don't know, right. You don't know how long the, you can ask how long the cask's been on, but if it's anything more than a few days, I must guarantee you're going to be getting a good level of, yeah. of of acetaldehyde, But yeah, I mean if if you're wanting to avoid it in Process. Yeah. I mean it's a part of every beer, right? It's it is a compound and I would have this made During fermentation, so you're always going to get some level of it. I think it's like yeah, well pitch correctly and healthfully. Yeah, it was pretty much a You're going to get a lot more than just acetaldehyde, but it can be a good one yeah, it, and it does mature away, so just avoid dropping, yeast too early or chilling too soon. If it's in there, you can generally leave it and it will mature out with, with yeast still in, in suspension or still working. and I think I, for that video, I've really experienced it a handful of times from my memory and then I think that it scarred me anyway, and yeah, I don't know, it just, it matures away. It's a good. It's a good thing to detect, well it's a good thing to taste throughout fermentation sometimes, on certain beers, because you'll start to pick up these in high levels, and then you'll know when it's not there as well, which I always think helps a lot. That's one of the main contributors to a hangover as well. Really? Because in Germany they say, diacetyl is a, I've heard that from a bunch of German brewers who say that diacetyl is the reason, I think I've even read it in concept. Which is, I dunno why on earth it'd be there, but, in like, the brewing book of the world. Yeah. Jeff's looking at me like the hell is come yeah, and I'm pretty sure they say that its daal is a, a cause of a, of a hangover as well. But is that how to hide? That's how died is definitely one of the things that gives you a hangover. Really. It's like, it's like a poison to your, to your body. It's what? No way. Some people are like genetically disposed to get like red face when they're drinking. Yeah, I mean, yeah, yeah, I remember I have a friend that gets like a really red chest. He calls it the reds and that's how that's probably one of the things like the like poison in your body yeah, it's not nice also in cigarettes as well. it's one of the negative aspects of smoking Yeah well, I didn't know that I didn't know that was that was one of the reasons it caused a headache Oh wow, I mean that puts me off even all those 3 day old caspers even more now. Yeah, yeah, yeah. Yeah, cool. Fire some more at me, dude. What about, I think we could probably after this discuss some, I don't know, like micro based ones? Before, what about trans to nonial? This is one that got a lot, I remember reading a lot about it, got a lot of hype and crafty a while back. But what, what about trans to nonial? Transitudinal. Transitudinal. Papery. Papery. yeah, papery, which is just, you know, like smelling a nice book in an old bookshelf. so, yeah, transitudinal is going to be, like, quite drying in your mouth as well. It's going to have an astringency to it. particularly on your rectum, like, so it's orthonasal, so orthonasal means when you breathe in. you're going to get it and you're going to smell that lovely papery book. Also on your retronasal, which is when you breathe outwards, And which is actually a time I should have discussed this earlier as well when we're talking about how to taste beer but there are some aromas that just the heat of being, you know inside your body and then on the way out You smell them again, for example metallic you can't actually smell a beer as metallic or it has to be crazy strong But from just from the top, but if you drink the beer you get it afterwards, which is pretty wild You see, when you're assessing people and if they can smell things, there can be a beer that literally tastes of a copper coin. and they don't realise because they're panicking and they're not, they're not assessing the beer by drinking it as well. so that's on the, the retronasal, which, which as, is the same for, trans 2 nonol, so papery. So, it's formed from the oxygenation of lipids during work production. And it binds to the proteins. It's not a bad thing, it's going to happen when it's in there. but the reason that it comes out is, is normally with high D. O. in your pack. so when we're talking about shelf life tasting recently, it's something that you might not, you're not going to be tasting it during production. So in your stop go and your like taste gates, it's not there. But if you're taking cans once a month and, and trying them and realising that whatever. Batch or even you know skew or all of your beer it's happening then probably an indicator of a do problem if you're not lucky enough to have meters and whatnot. Yeah, etc which Yeah Do you detect it a lot in craft beer? Some car scale often will cask beer I do in some craft breweries. You know, there's a few I can think of that You get it. It's just like Um You go into some breweries and you can't believe what they're doing in there. and sorry, that sounds so horrible, isn't it? and and sometimes yeah, sometimes I do not in like higher level stuff people that wear they're more Concentrating there's a few pale ales I can think of that. I've had it, you know by chance Yeah, but yeah, you do definitely see it around. It's not just a scary one and obviously like homebrewers are gonna get it etc, etc but papery, I wouldn't it's also one that you can confuse with a musty flavor yeah, which when, when you're training on different flavors, they always get confused, but musty, it comes more from, like mold or from like the packaging of raw materials. So something that's been stored in cardboard or wood. And the crown caps? Yeah, yeah, candied from the crown caps. Yeah, I remember that. Feels like going back a long way. Yeah, Chris just turned his hand. I thought you were turning a knob to say speak louder. But you were just I was thinking, yeah. Yeah, yeah. Musty is a slightly different aroma. And it's actually the smell of a cork as well. So, you know when they give you wine in the restaurant and they say, you smell it. That isn't them saying, do you think this wine is nice? Do you want to buy it? You have to buy it if it's been opened. The only reason you don't is if it's been corked. And it smells musty. And you can smell the cork, right? Yeah, yeah, yeah. I remember that from training. So, yeah. It's like, ooh. Oh, thanks. Yeah. Thanks, yeah. It makes me feel like it. Yeah, it makes you feel like you're assessing the wine. In fact, they're just saying, can you tell, smell that this wine isn't corked? because you can't send it back if it's been opened. so yeah, kind of trans too, a little bit. Reasonably simple. Yeah, because it's something I'm I mean, I was trained on it but I don't, I don't recall ever picking, well, I don't recall picking it up too often in craft beer so I asked you and I was just wondering if it was more because I'm not thinking about it, I'm not picking it up, or it's harder to detect with But you said you get it on the taste more, on the retronasal more than the that's, it's, it's, it has, it's really drying, if you actually get it in a beer properly, it's really drying and makes drinking it, like, hard work. Hmm. Yeah. Keep my eye out. well And you're not gonna get it with, like, macro products, because they're obviously so good with their DO. Yeah. Yeah. What about, okay, let's move into some more, contamination based off flavors. one which I'm probably quite interested in, a bit gross, is butyric acid. Butyric acid is everyone's favorite one to talk about. It is, yeah. It's gross. Yeah, it's totally gross, yeah. Well, it's, butyric acid, the, the, the flavor descriptor for it is baby sick. which is obviously disgusting, and if ever you smell a baby be sick then you're like, oh god. it's quickly worth saying, and this just, I know we keep occasionally saying this about, flavours being, like subjective or biased to other things. Yeah, yeah. Butyric acid is actually intentionally added to a lot of American chocolates. So, Hershey's chocolate is like the main example. There's some, like, ridiculous story about when they first started making chocolate in America. And in the UK, our dairy farms are right next to where they make chocolate, because the UK's not that big. But, in the US, their dairy farm might be so far away from where they were making the chocolate, that the milk would sour en route. well actually no, I think they soured it deliberately at the beginning, so it could then travel. Yeah. so butyric would be, would be in there, an aroma of butyric and then they'd make the chocolate and it would be associated with all the other things that were nice about chocolate. So American chocolatiers, from then onwards would put like, not Hershey's, like brands will add butyric acid to their chocolate so that it smells like what American people think chocolate is, is, tastes like. Like, if you compare a Cadbury Dairy Milk to a Hershey's, you can smell it. so it's not always a bad thing, like, it does exist. but when it comes to beer, it's not a pleasant thing. I don't think it's any beer styles that you're gonna want it in. it smells like baby sick or rancid oil. Bailey's Irish Cream? Yeah, that's a good one. it, yeah, it is, That's how I would remember it. Yeah, yeah. It smells like Christmas. Bailey's on ice. That's four examples better than the Hershey's one. I don't know, it was a really good story. You had me on the hook, so Ah, thanks, man. yeah, the, the Bailey's one is true. The taste of Christmas. It's the taste of Christmas? Yeah. Baby sickness. And it has a little bit on it. And, and once you've trained on butyric yeast It's a hundred percent. You can get it in there. That's, and it just shows the different places you get it. But I mean, if, if you get your session IPA and it has the, a little bit of that aroma on it, it's not pleasant. Right. in any way. so yeah, it, it's, it's, bacterial spoilage, but it it be produced quite early on with kind of sweet work. if you, you're adding sugar additions, as well, it can come around from sugars in that. And then, yeah, just spoilage in your beer afterwards. I mean, when we talk about butyric as well, we're kind of like, I would extend the conversation to be talking about like other acid producing bacteria. Yeah. That's going to be in, in your, your potential beer. I definitely won't say where I had this, but, in the past brewery, whether I worked there or I was consulting or whatever. we had some issues with, some like megasphera. acid producing that was just like incredibly horrible. and, and it hadn't, it evaded micro, and we had to do like a full breakdown investigation of the brewery and, and, and yeah, it was a thing of nightmares. Yeah, yeah, yeah. A hundred percent. the thing of nightmares and, and relevant and prevalent in, it arrived in cans, it arrived in kegs, and, and, Because of the sensory of it and the assessing and and we we we narrowed it down to batches that had been put through particular processes around the site so opening cans and whatnot and finding the finding the megasphere which has the aroma of like similar kind of babysit maybe more like wet dog It's a horrible fact when we first discovered it. We didn't know what it was So we gave it the number 2064 because that was the first batch that we found it in So we just called it 2 0 6 4 on site. So we were like, we were looking for 2 0 6 4 and it was mega through, has a biofilm, so it, it's, oh my God. So it's like a round in water, so you can like, go down your drain and then you can suddenly be spraying, you spraying around the brewery and it's in a drain and suddenly you sprayed it up to something else and it's gone into somewhere else. And it was everywhere. Well, actually it wasn't everywhere. we found it in a, in a particular place. But this is a conversation to ask me about. More, if you'll ever see me,'cause I don't wanna drop people in it but yeah, that was, it was picked up later from us on shelf life testing, and we managed to withdraw a lot of the product, that was out in the market so that it didn't get out there. but yeah, that's fine. So bacterial spoilage basically, so all these things are hygiene. yeah, and, and we were discussing earlier when we were getting some lunch before we did this, that. So many of the problems in the brewery are just like, are you cleaning enough? Yeah. Did you be cleaning more? Yeah. We were talking about the annoyance of people saying I've not had a problem yet. yeah. And, and for that reason, I'm not going to change my processes. Like, you know, have you found the problem? That's probably the better question, right? Yeah, yeah, exactly that. so yeah. butyric or just general acid producing bacteria is generally a hygiene issue. Yeah. yeah. What about, phenolics? So there's There's two types of phenolic that I'm aware of, which I think you can definitely tell me that's different, are the ones that are quite common. Yeah, the common ones. We always talk about, like phenolic for VG and for EP. VG, is like generally a positive thing, if you get it. So it's gonna be in some like, German style wheat beers, like, German style? Or is it wheat beers? Sorry, I've gone off. It's been a while since I've drunk a wheat beer, if I'm honest. Yeah, I don't drink them. Yeah, yeah, I do actually love, different wheat beers. But, yeah, Phenolic 4 VG is going to give you, like, some close, and those, those, you know, beautiful aromas. Whereas, I think, because we're leading on from spoilers, you're probably talking about Phenolic 4 EP. Yes. which, is more commonly, we're just going to call it Brett. you mind me just saying Brett? Yeah. yeah. so, yeah, so it's gonna come normally from, Brettanomyces yeast through fermentation if you want it. or, or probably could be there if you don't want it, because it's not gonna be, come from any Saccharomyces yeast. so, and that, or it might be in, in post pack, so that's just like a, a wild yeast contamination. that you're gonna get, the, sorry, the, the aroma of phenolic 4 EP or Brett is gonna be the common descriptor is, a band aid, a plaster, a plaster or I mean people say horse blanket. I personally have never seen I don't really know what horse blanket is a blanket that a horse lies on But people say horse blanket and I get it. It does kind of smell like a horse. yeah. but yeah a plaster a band aid horse blanket, so it's If a beer is not meant to have The aroma of 4 EP or botanomyces then you've got a real problem on your hands but if you meant it then fantastic. It's going to be one of the best beers, that you guys, Are going to get to drink. but again, that's like the issue there is going to be your micro So I go into so many breweries and they're doing no plating throughout and alike and they're sending off one in every Five batches to someone to assess but none of the four in between which is cool and I get that people don't have the money to do those things But yeah, that's going to be a micro issue for sure. Yeah. Yeah, and that's what this is where sensory is Probably to me one of my favorite quality pillars because It doesn't cost you much and you can okay. Some of this will be retrospective, right? So you found brett and your beer damage is kind of already done to some extent. I mean that's but it's you It doesn't have to be at the end. But yeah, you're right. Go on. Yeah, and I think it's just It's free to do in a way and you can just do it and then you can assess everything You can go deep dive after that. I think It's just that that's why this is so powerful because you can catch things Maybe even before they go into pack which is Obviously the optimum time to catch something, should you. and yeah, that's why I really like Sensory, because it's just, you can catch all of this without having to necessarily, I mean, plating is really good, but I mean, if you can't afford it, you don't have the, you know, the equipment, or the skills, or the time, then this is just a good way of assessing when something is going wrong and when it isn't. Yeah, no, I wholeheartedly agree. Far away my friend, we've got them all on our little list. We wrote when we were having lunch earlier a couple of things that we might want to talk about. if we were going to do it. that's all the that's all the compounds I have written down. Five compounds, I've only written 10. Yeah, exactly man, I used to train like 30 at a time. Be if anybody ever wants to talk with them, just get me on the phone. I might like taking out over a beer. Yeah, so I think that that's probably, we'll go, that's a good amount of compounds to go over in good detail. I don't know if there's any honourable mentions you want to You want to add to that list, but I think it's pretty comprehensive of common ones. I've I think I think the reason we wanted to talk about those a little bit because we What I think we were trying to do then was to say what they smell like how they occur And if possible how to fix them and whatnot. Yeah, the reason sensory works to pick up problems. I would also say that sensory is incredibly powerful for for as a force for good like I've trained quite a lot on different hop Different hop aromas and then that so the way we're describing them now in the same way You could do positive things or talk about the difference between grainy and malty. Do you know what I mean? Yeah, and and they're different parts of Of the aromas that you get from malt that that can be isolated and if you if you learn the differences Then your your dialogue becomes different. So I think It's worth saying that isolating particular things Can also be for positive flavors Yes, yeah, yeah, absolutely. yeah, we spend a lot of time talking about the bad when, when we can use this, we can use our noses to create a much better product as well as just stopping bad ones. Yeah. yeah. So I, I like, if I think what, something that I really want every brewer to do is to sit down and drink beer. Yeah. and, and talk about it and. I dunno. I'm ling on getting to I, but it leads us on to like, I think common mistakes within sensory I think was something I wanted to discuss about, and. Maybe that is like one of the key ones is the common mistakes is Um, always be polite about other people's bier A hundred percent, yeah. So don't be like, oh this is disgusting, it's got diacetyl in it. And then, you know, just, you don't know if that's supposed to be there, it's not your place to say. Yeah, always, I think I find myself often really frustrated with a person who is telling everyone so loudly their views and what they think. Yeah. in terms of, you know, what we're talking about here. Everybody's view is valid and don't, don't be, outshouted by someone who's more senior than you. Yeah. Or thinks they know more than you. yeah, it's, it's the power of two ears, one mouth. It's like listening and building your, what you're going to say before you say it. Yeah. Yeah, yeah. And, and maybe echo some of the things that you said in the, in the, in the first one. Episode was you know, not succumbing to it or not allowing influence to happen. So I get like group discussions are great, but with sensory Just as jess would say if someone starts telling you this has got passion fruit in even though probably almost certainly doesn't it will trigger In your head and you'll be like, okay now i'm beginning to get it and it becomes quite I don't know quite hard and confusing and also that person of influence in the brewery shouldn't be leading it. They shouldn't be i've seen in places i've been where it's like You know, they'll be A group of people and it'd be like the head brewer production director and then he'll say yeah Yeah, this beer is okay And then it's going to take someone pretty bold to stand up and it then it turns into more of a social thing Social like issue pointing out rather than it being just a science which it is and I always think that's like quite a common mistake is You know it being led by someone who has that influence in the brewery. Yeah very much. So if you've got someone that can add it into their their day You And obviously it's a luxury to have but well, it's not a luxury actually It should be a part of just generally setting up a quality program. I think in the uk where We're really lax about it if you go to the states it's like as essential as any other part of your quality program and in many ways, you know They're ahead of us in the way. They're making a bit because they think about that. But yeah Cool, man Well, Geoffrey, is there anything else you want to throw into this mix? not really. That was really nice that you requested to pick my brain about things that I don't talk about too much anymore. but yeah, if anyone wants to have a chat or whatever, leave my contact details in the show notes. this kind of stuff, it's not what I talk about on a day to day, but I love talking about it every bit. and if, if I ever come to the brewery, we can, I'm sure, catch up. and, but yeah, I would recommend anybody to go and buy some flavor standards from somewhere. Just look online, and then, and just train up a little bit and then add it into your, add it into your daily practice and program your SOPs. Um, and, uh, yeah, don't be a stranger. Yeah, I love that and it's been really fun for me. when we talked about it before, I was just, I've been out of a bit. brewery production environment for, I mean big production environment for like, you know, two, two and a bit years now, I'd guess. So it was quite, it was really refreshing being able to talk about sensory. I forgot how much I really loved it as a topic. and it used to be like second language to me, in the brewery. It's so, it was so important to what we did and we detected so many problems. I've probably talked about some and it solved so many, it helped me. Bring so many issues to our attention. We then solved it was such a it was one of the better things that ever happened to Me my career was going through that sensory training. I think it was it was awesome. So really hope that everyone got to Have a slice of that what it's like Pick up some flavors. I'd also say go on to ASBC and just check out the man. Yes for what not and then And any questions, you can always know where to ask. You can ask me, you can ask Jethro, you can ask, yeah. There's always a good outlet in case anyone has any questions. So yeah. Cool. Cheers, Chris. Thank you so much, Jethro. Cheers to everyone, mate. See you later. Thank you so much for listening everyone. I really hope you enjoyed the episode with Jethro. I really love two parters because it really gives you the ability to go really deep into a subject and I think sensory is such a fascinating and amazing subject. So I really hope you enjoyed the episode. Please hit me up with your comments, feedback, suggestions for anything you want, any new topics. If you wanted to hear a different type of format, please let me know. You can always reach out to me over LinkedIn or Instagram. So thank you so much for listening and I'll catch you on the next episode of the Modern Brewer Podcast.