Why your Coffee is Sour/Bitter! (and how to fix it)

[Applause] finally oh oh how do I fix this is it is it sour no it's bitter it's bitter wait is it sour now that cute little dramatization is probably what you go through very often whether it's with Filter coffee or with espresso you get a little confused is it sour is it bitter which direction should you go and this is actually a phenomenon that occurs in sensory science the sour bitter confusion so many of you are not in the wrong for having this confusion it can be very difficult to tell them apart since the Direction

you need to go with your extraction is completely dependent on your taste buddies you need to know which one it is so you make the right choice so in today's video we're going to break down what is sour what is bitter what causes them and a little pallet training so that you can get better to get good on how to make those distinctions so let's get right into it if you're new to the channel I'm Lance and we do some uh Crazy Coffee stuff here lots of it gets really nerdy into the science into the

weeds and so that's just a part of what you're going to have to suffer through in today today's video to get to those fun little taste experiments near the end of course you can always skip to the end but I'd prefer you to watch through because I put a lot of work in these videos and uh hitting the like And subscribe is very helpful for me but anyway both bitterness and sourness are attributed to acids and coffees but where do those acids come from in green coffee you have three that are actually grown inside the

Cherry itself citric acidity you have malic aity and you have cinic acid these are the all part of the citric acid cycle which is what is used as the plant in order to bring energy to it photosynthesis yada yada yada we won't get two in the weeds there all these other acids that are contributing to flavor and to bitterness into astringency or whatever it might be are all coming through the processing as well as the roasting and the processing this is going to dictate to a large degree the amount of acetic acid in your coffee

now acetic acid are actually really small compounds but they're very powerful they're very potent so whenever you're smelling a coffee and you think you smell orange or you think you smell hair you're not actually smelling the citric or the malic acidity in sensory science coffee scientists are not quite sure what it is that's going on but it's definitely some sort of relationship going on between the different acidities and how we're receiving it in our receptors there's actually a defect in coffee called an acetic defect where it is essentially been processed for too long and there

is a high concentration of these acetic acid compounds that are kind of taking away from the Flavor of the coffee and being too to kind of vinegary so actually for coffees to have this kind of pronounced acetic acid this is coming from the processing for the most part so how much you're fermenting it so a natural process will have more acetic acid than a washed a Carbonic mation will have more than just a normal natural and so on and so forth the more you're processing it for the most part the more acetic acid is being

formed but then during roasting you get a lot of other acids that are being created like lactic and so forth but a big one that we need to talk about is chlorogenic acid the pH of green coffee would need to be around two for the amount of CGA in it to actually be an acid so they actually say it's not an acid in that form in green coffee it turns into the acid during roasting bitterness is actually attributed in a brew to chlorogenic acid lactones not chlorogenic acid it's the breakdown of chlorogenic acid which does

break down into cafeic and quinic acid there's an a misunderstanding that quinic acid actually gives off bitterness but there's no actual proof of that there's just kind of speculation around the idea that quinic acid attributes to bitterness but what is kind of known is that it's actually these chlorogenic acid lactones and fin indines these are what are contributing to that bitterness now when it comes to sourness that can be attributed to kind of overall acidity a really interesting study that has actually been done in two separate locations I know that Dr s SM has done

this as well as Morton munchow at Coffee mind Academy you can have a coffee with more citric acidity but doesn't taste as citrusy as something with quite a bit less citric acidity the biggest example here is that Brazilian coffees especially natural Brazilian coffees have a much higher citric acidity count than Kenya coffees do that's wild you would assume Kenya coffees being known as the most citrusy coffees kind of on the market would have the highest citric acidity count but they don't they're more acidic overall than these Brazilian coffees and that's what's kind of giving us

that perception of acidity but in reality it's not because of the citric acid that is inside of the Kenya coffee itself so we know that sourness is coming from the amount of acidity in a coffee and how it's kind of interplaying with our receptors in our mouth but we're not actually sure how we're getting those specific flavors whether it is a tangerine or whether it is a plum or whatever it might be that might be correlated with m or with citric it's not from the acids themselves though it is based off of a lot more

convoluted things than that which is welcome to coffee so how are we able to control our extraction in order to make this relevant for us at home or us in a cafe how can we use this knowledge this understanding of where the bitterness comes from where the sourness comes from how can we improve our coffees well first of all we know that from Morton munchow but this is also very logical but he has in a study that the further you roast a coffee the more bitter it's going to come but he was actually able to

show this because of this kind of process called pyrolysis where essentially the darker you're roasting something the hotter it's getting and the drier the material is the more you're going to be creating these bitter compounds that are going to overtake the cup and get incredibly bitter so there is a direct correlation between a darker roasted coffee and more bitter compounds in this study he also shows the breakdown of the presence of acids on five different coffees two from Brazil two from Kenya and one from Bolivia and how they are affected over time in the roast

Pro process so they roasted it roasted every coffee light medium and dark and they trace the presence of these acids throughout this different kind of roast parameters interestingly none of them really change with the exception of citric malic and chlorogenic acid now some of the other acids didn't move at all some of them barely increased some of them barely decreased but for the most part they all acted the same through every coffee through each of these different roast profiles which I think is really interesting and in fact when you take into account that in a

static dose of about 15 gram you'll have more dark roasted coffee beans in a 15 gam dose than you would with a light roasted coffee bean in a 15 gam dose and the amount of acid is based per Bean essentially so even if you have 30 or 40% less citric and less malic acidity when you have more beans in a given dose of dark roast it's close to a wash as far as the amount of acid that is present in your coffee you're not actually lessening the amount of acidity when you go with a darker

roast you're actually just lessening the perceived acidity so I always get a little um I don't know flustered or confused when people say I can't drink light roast because of my acid reflux because the amount of acid in the two are almost ENT identical it's the perception of it that is going to change so we need to understand the difference between actual reality and perception our mouths are really crazy lots of things going on and I have a very fun follow-up video that I'm going to do on astringency with a brand new dissertation that was

released just a couple of years ago on potential meano receptors in our tongue that are similar to trip receptors it's going to be a lot of it's going to be a lot of fun a lot of nerdiness and a lot of cool new theories on how body and astringency are perceived in our mouth with potential uh new functions by mechano receptors in our mouth but anyway we'll get to that in this follow-up video on astringency and how to detect that and what it actually means and how we can understand what that is but let's shift

back our Focus to this video now in addition to roasting the presence of acids are very interesting when it comes to Brewing again Dr s SM who's giving us all the good data actually has done a lot of testing with the development of these volor organic compounds that's the direct contribut to taste and taste perception and how they're affected during the extraction process it depends on temperature depends on time depends on extraction yield but let's just assume typical parameters so in espresso extraction this also applies to filter coffee let's assume a an espresso extraction that's

typical you know around 90 some odd degrees Celsius around a 1:2 ratio whatever we're getting around 19 20% extraction or well we'll leave that open-ended it can go up to imp perpetuity some might assume that all of the VA organic compounds kind of continually increasing throughout the shot in fact what happens is early on the concentration of those kind of ones that we're wanting that are directly affecting our sensory experience with these different fruits and sweetness and whatever it might be as long as it's in the coffee those are kind of at their full concentration

at their highest concentration I should say early on in the extraction these acids are incredibly easy to break down and to dissolve and to get into your cup there are other things that are being extracted that don't really begin to go up until we hit that 19 or 20% extraction there are some that are static throughout but the ones that we're really interested in kind of Peak at around that 18 to 19% which is contrary to a lot of recent movements within the coffee world of optimizing extraction to the highest amount possible to get the

best cup a lot of people will say we need to get the highest extraction without AR stringency and that's the best cup it's the juiciest cup it's the tastiest cup when in reality the science would say otherwise so if you have a really sour coffee the way we're able to balance it out and get into the sweet zone is from a balancing act of those more bitter components that will come with a further extraction so they continue to break down and to kind of get into your coffee as the extraction is continuing this is why

that whole Frozen balls type of uh thing happened just a few years ago this idea of retaining volatile organic compounds that are released early on that can dissipate throughout extraction so you kind of freeze concentrate them into your cup with this Frozen ball remove that and it allows the extraction to continue this is because so many of these are so quickly extracted they're so so volatile that they come out and they're going to want to leave of course there are some leniencies taken with that study and they're showing that 40% are lost in that first

little bit in reality not all of those are great but what we do know is in a typical extraction which is why I said typical earlier CU that's what was done in the study they are optimized they are heightened they're at their fullest concentration at a much lower extraction percentage than what people are used to kind of chasing which is 22% and sometimes 23 or 24% in that range we actually have a much lower concentration over the full beverage of those really nice uh uh or organic compounds so to hit an 18 or 19% extraction

you don't really need that much yield in fact the extraction happens so rapidly that you could pull a one to one shot and you could hit around a 17 or 18% extraction going to 1 to2 ratio you're probably only bumping your extraction percentage a couple of percentage points and it goes less and less and less as you're pushing the extraction until essentially we Plateau with just barely tiny little incremental gains and so the concentration of those of those or compounds are going to lessen more and more drastically as we push our extraction because to push

the extraction we need a lot more a copious amount more water and it will lessen the concentration so it will get more and more subtle as we're introducing more bitter compounds later the extraction early in the extraction yummy we get those crazy acids those Vol organic compounds that are contributing to the Tasties in our cup but they can be overwhelming they can be too intense at those lower extraction yields so we need to push the extraction to balance it out with maybe more bitter compounds but then as we keep pushing it we're drowning out those

Tasties and we're bringing up those yuckies okay so we need to have a balance between this undere extraction quote unquote every coffee is relative in what its undere extraction phase is and we need to balance it with the overe extraction quote unquote again that's another relative term that's based off the coffee and your pet preferences sourness we don't want to think about where it's hitting on our tongue that whole tongue thing for that was put out in 1901 oh you get sourness on the side and bitterness on the back that's all BS that was completely

debunked years and years ago so we're not going to pay attention to oh I'm getting at this on the side now there you can be psychologically fooled into thinking something is going on in in one part of your tongue or another but all the receptors are evenly distributed across the tongue you might think that you're having more biting reaction on the sides of your tongue I'm not negating that experience but is it actually a reality that you have stronger taste buds on the side of your tongues no not necessarily it's depending on where the Pia

is for specific specific type of uh reactions to uh to different tastes and to The receptors in your mouth instead we need to ask the question of when and how when is The Sensation that you can't decide is sour or bitter when is it happening and how is it happening with sourness you're going to have an upfront kind of hit of something that is sharp High tones and is quickly fading it doesn't linger that long unless you have a really thick espresso and it's the espresso that is kind of keeping it on your tongue due

to viscosity but but for the most part it's a quickly fleeting kind of experience that is biting and immediate what we're talking about or referring to with bitterness is a more creeping sensation something that doesn't necessarily hit you like a Mac Truck right up front like sourness will but something that creeps up tends to cause a drying sensation and forces a something that lasts quite a while it's not a quick hitter it's more low as opposed to high with sourness and it is essentially a big marker of it is the dryness that might be occurring

now there's also a stringency which is a whole different thing alog together with a different uh a different contributor to it which we will get in another juicy video coming up but right now we're talking about just simply bitterness so having a reaction that is a slowly creeping more of a low type of thing going on that can be drying drying out your mouth okay I want you to go grab lemon juice or go grab some sort of vinegar it can be white vinegar it can be apple cider vinegar whatever get some vinegar I grabbed

some lemon juice I've got some vinegar you know we're just going to have these right here then I want you to run in or to your kitchen get some cocoa powder or grab some black tea if you have black tea I uh actually couldn't find my black tea but I've got this Tupperware of cocoa powder these are going to represent sourness so it's an extreme example obviously but it's because we want to train ourselves to understand what that intense upfront not lingering like sharp acidity is and we want to train what that bitterness is what

that dryness is so the way we're going to do this is just take a little bit of your lemon or your vinegar or whatever it is and we're just going to TOS in a cup there we go and then for the bitterness over steep of black tea if you have black tea and you don't have cocoa or if you have cocoa powder just take a little scoop toss it in a bowl and we're going to add some water to it now that we have our little Solutions ready just take a little sip of your lemon

juice or something woo and notice how it's an immediate hit of I mean it's already gone for me but it's an immediate upfront sharp hit it's like punching your taste buds and it's got really high tones about it okay it's like it's bringing you to another level upstairs and you're but it's gone mine's already gone it's like Wasabi with spiciness it hits you quickly whereas like a a hot habanero or something will sit there and it'll just burn you up for 20 minutes now you're going to meet imediately compare that with bitterness so we're going

to take our cocoa or whatever solution you use you sip it immediately there's nothing really there but as it sits it starts to creep up and you get some dryness that's going on in your mouth and you have kind of this bitterness it's kind of like a not stinging but kind of a um it's really hard to describe obviously and that's why I want you to taste but kind of a lingering um not biting cuz that that's a word used for uh sourness for the most part but there is sort of a a clawing type

of feeling that's going on and then you know take another sip of it of the Coke or the bitter one allow it to linger allow it to sit there and and to kind of try to remember what what it feels like and if you do have very specific feelings on parts of your tongue you can remember that as well just because it's wrong doesn't mean it's not helpful and then we're going to go back to the sour one woo that's crazy thankfully it's gone now all right understand the sourness and the bitterness that are present

right here and then what we're going to do is take this kind of this understanding this memory this experience and we're going to apply it to an espresso and to a pourover which will hopefully help you understand those differences quite a bit the first thing I want to do is essentially what a salami shot is first we're going to prepare an espresso and the first 10 or 15 gram whatever it is to be about half your dose a little bit over half your dose worth of espresso output we're going to have in one cup and

we're going to switch the cup after about 10 that 10 gram comes out 10 15 gram and then the rest of your shot whatever you have it dialed into let it go into the second cup then we're going to taste those two now in theory that first bit should have about a 15% extraction yield and that's going to be the the majority of those acids that are contributing to sourness then the second part of that cup is going to be a lot of the other things that are coming out that tend to balance out your

espresso that tend to lessen the concentration of those really sour presenting elements that come out early on same thing can be in a pourover after your Bloom and maybe a 50 g pore following your Bloom just switch your decanter out or have it going into a cup and pour the rest of your pore over into a separate vessel and then taste those two side by side all right now another way you can do as I said there's a second way is you can intentionally undere extract an espresso so if you have it dialed in to

a 1 to two do a one: one and then if you're Doo 1 to two do like a one to four and taste those side by side to have extremes I really like splitting the beverage though because we can actually do part we can kind of do our own scientific process where we're pinpointing where the majority of these uh contributing factors are actually apparent so in the video I'm just going to do espresso but you all can do the pourover at home if that's what you're doing and you're going to have a similar uh re

reaction just make sure you don't do too much in that first bit cuz the extraction happens pretty rapidly so you want to have that high concentration of those intense acidic compounds that are like I said um the volid organic compounds that are contributing to the flavor perception so let's get this shot going and I'm actually using a pretty Darkly roasted coffee because I want to show that even in dark roast coffees you're going to have an intense amount of acidity in there in fact acetic acid continues to increase during the roasting process even though citric

and mallet goes down and again with a 20 gam dose of this there are more beans in it than in a lighter roasted coffee now the perception obviously goes down but there's still a lot of acidity in here that can cause a very sour shot so we're going to pull out the first I don't know maybe 15 gam of coffee cuz I have a 20 G dose and then I'll switch the cups out so let's do it all right so there we have it we got about roughly the first 15 G there roughly the last

25 G there so as you can see right off the bat the first bit is a lot darker it's a lot more concentrated but also there's more fines that have been washed into the cup so this is actually a very difficult thing because you're going to have bitterness as well in this first bit because you have physical cell wall fragments fines that have made it through that are going to be contributing to a bitterness so I always tell people to make sure that uh you have to understand that there are going to be some Grinders

that produce a lot more fines there are going to be some baskets that allow more fines to go through all these different things can and darker roasted coffees will create more fines which means more will get into your cup so understand that you'll also be having some bitterness so if you go I get sourness and bitterness the culprits can be high fines production so lots of fines migration or tiger striping which is some people call it modeling there can also be the issue of it inconsistent or uneven extraction uh which could cause it to be

sour and bitter at the same time having both that sharp acidity and the lingering bitterness but also a really dark gasted coffee is likely just going to be bitter throughout the whole extraction anyway due to the uh polyphenols the melanins whatever it might be so anyway let's take a sip of the sour one first yeah acidity is pretty high there actually for a dark roast and it's very very salty that's another thing is undere extracted can be very salt salty so if you have a saltiness a biting even Savory that can be a sign of

undere extraction and that is awful that the wow and then this one should be largely bitter coating sits there drying things like that so yep and that's exactly what's going on as it sits there the dryness is starting to really creep in onto my tongue it's oh and as I'm breathing it's getting like worse a fun to do with dark roast but it's when you mix these two together it's where you're able to lessen the concentration that was in the first because we've now added a lot of volume devoid largely of those uh compounds so

when it's devoid of those compounds it's like we're diluting it right we're if if we have something with lots of compounds in this hand something with no compounds in this hand and we dump this into the initial one the concentration goes down even though the amount of free floaters are still there right cuz we've doubled the volume but maintain the same amount inside so the concentration goes into half or whatever it might be based off of the volumes you're using so that is what's going on in our extraction process is we are essentially trying to

balance the amount the concentration of what's coming out early on with that which is coming out later on so all dialing in is is taking the concentration we got early out on of those things which make coffee interesting and diluting it with things that make it maybe a bit less interesting but maybe necessary so whenever you are dialing in your coffee what you need to pay attention to is where and how is the FL the flavor affecting you that might be off-putting is it bitter is it drying is it a low creeping type of sensation

or is it sour is it harsh is it biting is that a high type of Sensation that hits you immediately how and where is it affecting you then make changes based off of that of course if you're sour that means you need to increase the extraction you can do this in a plethora of ways that I've covered in many past tutorials on espresso but a simple way is just pulling out a little bit extra on your next shot so instead of changing anything don't worry about it don't change your grind size don't mess things up

just five more grams into your cup that will give you a huge difference because regardless of how you're pulling it you're if you're doing a one to two you were definitely hitting the range of 18 to 19% if not a little bit higher regardless of your grinder and setup you're likely not hitting below 18 it's actually kind of impressive when people are hitting 16 and 177% unless they're doing massive rros and so just a little bit more is going to greatly change the effect in your cup if it's drying if it's bitter if it has

these other qualities lessen it you can either up doose into your basket so adding more coffee or even easier do five grams less do just a little bit less output and you'll be shocked at how big of a difference it can have unless you're you know the bigger the ratio you're at the more change you're going to need when it's overe extracted right cuz if you're doing a 1:3 ratio so 20 in 60 out for instance you may need to do 20 G Less on the output in order to get it down where you have

a lot more of that kind of acidity presentation coming out now of course there are coffees that are more inherently acidic as far as their roast presentation than others like the one I use today is a really dark gross Neapolitan style coffee the acidity in it is going to be much lower regardless of where I pull it if you had a really light coffee that overall has a higher presentation of acidity then of course you're going to still get acidity well past 19% the point of me saying that is not that you lose all acidity

once you pass 19% it's at the highest concentration of those volatile organic compounds that contribute to flavor are around that 19% you can still get really acidic coffees at 23% depending on your coffee the darker the roast the less potential there is for that but it is still there that was a shiz ton of talking I hope it was helpful though I hope kind of seeing behind the curtain of where science is right now with coffee chemistry is helpful and I hope that these little taste you know these little taste exercises will Aid you in

bettering your coffee at home because that's what we're all here for better coffee regardless of the extraction yield regardless of the efficacy of extraction regardless of your equipment at home regardless of of the coffee you like regardless of the style of espresso you enjoy or pourover you enjoy we need to understand how these things are affected because taste is subjective and the way that you perceive your coffee is going to be different than the way I perceive my coffee and the way I enjoy my coffee so it's important to to kind of equip you all

with these type of weapons in Your Arsenal so you can go through and dominate your spro all right that's what we're here to do anyway thank you so much for watching this video I hope again I hope it was helpful and if you still haven't done it please hit the like And subscribe if you enjoyed the content uh and look forward to part two on AR stringency because that one I'm honestly even more excited about because it is a kind of Uncharted Territory in the coffee Science World and uh it's going to be real nerdy

thank you so much I hope you brew something tasty today and cheers