so the aim of today is to better understand wine faults and if you are joining us with a tasting kit you will also get to practice recognizing the those faults so identifying those faults later on my name is sit I'm going to uh go forward to the next uh slide now and I have a company called The Art of tasting I run classes like these teaching people about flavors and Fs commonly found in wine as well as in beer I have a master of science in sensory science so that's the study of flavor perception the study of the Sens of smell and taste I currently hold my level three Award of the wct and I'm currently trying to get the level four S the diploma I'm also an advanced cicerone so cicerone is the beer equivalent of a somier so I know a thing or two about beer as well I've studied at the University of vening so let me give you uh some quick setup instructions in case you're are joining us with the wi tasting kit you will need at least two identical glasses like this but even better is to use 11 so I'm going to quickly show you the setup this is where I have all my uh wines preport U but if you're joining us just with two identical glasses grab your fils that are called reference and number one and then pour your reference bottle inside one of the glasses and then number one into the other glass fantastic so then you should have two glasses preport that you will assess later on while we're setting up I'm going to in the meantime tell you about what exactly is a wine fault and these are generally considered undesirable flavors so unpleasant flavors in wine they detract from quality so the overall quality of the wine and it's important to keep in mind with each of the 10 flavors that we'll be discussing that's going to massively depend on the wine style so in some wine Styles certain faults are completely acceptable and they can even contribute to complexity of wine and in other styles that will be completely unacceptable then the level of faults so like in small quantities some faults are actually okay but then in uh other levels at higher levels they become objectionable so let me introduce you the the first sample of today and if you're tasting along smell the reference glass and SM SML glass number one and you should be able to tell the difference immediately these are two wines that have the same base wine they're based on a neutral white wine and then to Glass number one is a single flavor compound added it's a molecule that have added in a small quantity and that molecule is called TCA which is short of Tri chloro anol and I'm giving you a couple of uh descriptors here for most people they would describe this as the smell of wet cardboards and this indeed is the very common descriptor of cork Tain but there's some other descriptors of cork taint as well so think of swimming pool as well as moldy Dum Cellar what is graph is showing you basically I've asked 20 wine tasters give me some descriptors of this wine sample with added TCA and then about half the people so 10 out of 20 people they will say it smells of wet cardboard and the other descriptors are slightly less common descriptors but everyone has their own personal associations with a particular wine flavor so there's not a one siiz fits all the scriptor but wet cardboard seems to be the one that's most commonly agreed on if you're tasting along with this it would be great uh if you have another Association that's not on the list then type it in the chat and that will help us generate a of other associations so maybe you think it smells of leather for example then by all means put it in the chat that will help us understand better better how these wine folds are perceived so let's discuss where this uh fault originates from TCA is short for trior anol which means it is a chlorine containing compound and that chlorine can be traced all the way back to the cork growing industry so the so so the industry that focuses on growing cork trees and let me show you just in a in this plot how that this exactly formed so this is uh in detail how TCA or corane is formed let's have a look at the chlorine component so that's going to be a component of biocides biocides are herbicides or pesticides they're very commonly used in the cork tree growing environment that is sucked up by the root of the tree then it binds with certain phenolic compounds that are present in the bark so that are present in the in in the tree itself and that forms something called TCP which you might be familiar with that's also a commercial product it's a very effective antiseptic antiseptic means that it kills microorganisms such as molds and in the in the case of cork taint basically it's molds growing in the cork that are trying to get rid of TCP by turning it into TCA so TCP is toxic to them but TCA isn't so this is basically a coping mechanism of those molds so this is a quite a common problem still about one in a 100 bottles these days will be affected by Caines uh however it used to be a lot more in the past like back in the days we would be looking at around eight bottles of every 100 bottles that would be affected by cork tanks back then cork trees were produced in a slightly different way and the use of chlorine containing herbicides were particularly more common cor production from those trees were it was also more common to use certain bleaching agents containing chlorine and thereby also increasing the likelihood of TCA so it's important to keep in mind that TCA is produced by molds and not by IIA or Yeast that you might be familiar more familiar with in the production of wine molds can actually not tolerate alcoholic conditions at all that means that there will not never be mold growth in the actual wine but the molds always have to grow on something else and in most of the cases that's going to be the C but this really musty wet uh damp cardboard smell can also be the source uh can also be present from other sources such as contaminated barrels or other equipment in a winery that is contaminated with molds and then the TCA basically transfers from the infected equipment into the wine so these these cases are a little bit rarer but sometimes even in the cases of screw cap fitted bottles you might see a wet cardboard taint but then you would be looking at an entire batch that is runes but it's it's a lot less common than cork tains in bottles I can see um we have some other descriptors as well uh still seller yes I can relate to that as well when I'm smelling glass number one so moving on let's have a look at the detection threshold so what I'm showing you in the slides here in uh the bottom right is the minimum level of this flavor that has to be present in wine before it gives that wet cardboard flavor and this is press in two nanog per liter and a nanogram that is really very very little you might be more familiar with the unit of milligrams that is more or less a sugar granule but a nanogram is a millionth of a milligram so we're looking at a millionth of a sugar granule of this compound in a wine that gives off such an an awful uh taint and you can also express it in a volume percentage so I don't know if you can see my uh cursor over here actually on the screen be not quite nice stuff that confirmed I'm just hovering over the the percentage of TCA here and that is 0.00 a lot of zeros uh 3% and that is really very little especially if you compare it with alcohol so this wine here in front of you contains 12% alcohol and the alcoh is not even all that noticeable but the TCA smells really really uh quite strong and um and it goes to show really that we are very highly sensitive to some flavor compounds and not really all that sensitive to others so uh let's move on if you're trying the tasting kit be well worth to Tasty samples and I can imagine if you're not particularly excited to try cork tainted wine but it's a very useful uh learning experience and you will notice that some of these faults are much easier to get on the nose whereas others are much easier to get on the palet so you could start with the reference wine you can use a spit tun if you like of course all of the added flavors I'm using in this these kits are safe to smell and to taste they're food grades they're the same compounds that occur naturally in wine and there are the same compounds that cause these faults and I've also added them in a quantity that is very representable of when this fault is H is a normal problem so let's try that in leave yes uh very dominant on the pallette as well moving on to the second sample so you can simply empty the glass number one into your uh spatoon so that is the that is the glass that had the wet cardboard and keep hold of your reference glass please and then in the second glass you can fill your sample which is numbered two to and if you have already preport everything then you don't have to do anything but this would be the time to empty empty the wet cardboard and then pour glass number two if you're following this later on you could also pause the video here and try to work out what um glass number two smells like before any prior information but for the sake of keeping the velocity a bit higher I'm just going to uh go to sample number two now and that is the smell of Bru Apple and the smell of Bru apple is caused by an aromatic compound called acet Alid and there's a different few different descriptors here most people can relate to like a bruised Apple smell or almost like a green apple like a granny smith all there descriptors for acetal deide are paint and also carved pumpkin so if you slice a pumpkin in the middle and you smell the inside with the all the threads and the the seeds then that kind of releases the same smell it has that same aromatic compound uh that is released there so a wide range of different descriptors because this is an aromatic compound that's not only present in wine but also in other sources in nature so let's have a look what the origins are of that flavor there's basically two roots that can cause this fault uh because acetonide is both produced during fermentation but it's also an oxidation flavor of wine during fermentation in very simple terms yeast converts sugar into acetal theide and subsequently in alcohol so in other words acet alide is an intermediate product in a conversion by yeast from sugar to uh alcohol or ethanol in chemical terms that means that whenever you're smelling a Bru Apple flavor in wine it could be the sign that fermentation is not fully completed yet maybe it's only uh only occurred for a few days and the wine maker was in a bit of a rush to release that wine onto the market as soon as possible it could also be the case that your fermentation was stuck and when I mean stuck then not everything is going according to plan because yeast is stressed it's unhappy about the fermentation conditions and it might stop fermenting before your fermentation is fully completed and all that sugar is neatly convert in uh to alcohol then the other origin of acet alide is that of oxidation so it's also the direct oxidation product of alcohol that means that much later in its life when a bottle is opened a wine bottle is opened for too long for example you can get higher levels of acet alide as a simple oxidation mechanism so exposure to air will result in your alcohol converting into AET alides giving that bruised Apple smell and that's really the same process when an apple is bruised as well it's breaking the seal the skin of the apple and it will start to oxidize even during the wine production process at some point uh small amounts of oxygen can influence wine maybe during fermentation or during aging and that will also lead to elevated levels of acetal heide there's one particular type of yeast known to produce high levels of bruised apple and that is going to be Flor so in ferries you will always have a noticeable level of bruised apple and in that particular wine style it's not considered the fault it's consider considered to contribute to the complexity of these wines but in most other styles it would be considered the fault so for example imagine um a Muscat something that's supposed to have a lot of floral aromatics you really don't want any bruised Apple characters to sort of mask all the desirable floral flavors so in most wine Styles this would be unacceptable there's a handful of styles where a little bit of bruis Apple character is actually acceptable so that's slightly different from Cork taint where cork Tain is unacceptable in all styles it's just always a problem it's always a defect with Bru apple is more a case of context so if it if it is suitable in a particular style and I can see a question coming up from the chat can a cork that does not seal well the bottle cause uh it and I think you're referring to acetal theide and absolutely yes so bottle closures are playing a major effect here so there's particular screw caps that can seal a bottle very well and protects very well against oxygen and some bottle clo might be of lower quality they will allow a little bit of air coming through and it can lead to elevated levels of acetal height so absolutely yes um in case I'm missing any questions at the end of the webinar I will quickly run through the chat and then answer any questions that I might have overlooked but um thanks for um thanks for asking um in terms of prevention because most wine makers will try to limit the levels of acet alide um managing oxygen so working a bit more protectively in the winery yeast strains so as discussed some yeast strains are known to produce high levels of acetal and other lower levels so if you're B buying your cultured yeast from a laboratory or a supplier such as lamant it will usually give specifications as to how much acet alide that strain is known to produce so for oxide or SO2 is a very common additive in wine and it has two purposes one against oxidation and ones and also against microbes so it has antimicrobial activity SO2 immediately binds to acetal height so it's a way to it's sort of a quick fix against two high levels of acet Alid because so SO2 will simply bind to it and in that bind form it doesn't have a flavor at all right moving on to Glass number three which is the smell of brown sugar uh once again I'm showing a chart of about 20 wine taster that have given descriptors for this particular flavor compound and there's a lot of different descriptors ranging from sweet ones such as brown sugar caramel but also spice ones such as curry powder uh and soy sauce so that's a couple of different uh different ways you can you can look at this flavor okay and this is a further oxidation compound flavors such as caramel brown sugar they develop uh during oxygen exposure and it's a bit different from acet alide in the sense that it's not produced by yeast at all so this is a more bit of a strict oxidation compound and there's a lot of factors that play a role in wine as to how much it is protected against oxygen let me start with one of them which is tanins tannins protect very well against oxygen and that's the reason why flavors such as brown sugar and other oxidation nodes are really more common to develop in white wine compared with red wines so red wines have that bit of a natural protection against it acidity being an a different major factor so higher acidity will protect better against oxygen and I'm putting down Vineyard conditions here as well because in warmer conditions in warmer climate that acidity of grapes tends to drop massively and that predisposes grapes to um to produce wine that's a bit more susceptible more prone to oxidation I've already mentioned that so SO2 is a factor in oxidation as well as bottle closure so bottle closure some may be a bit more affected than others another factor is that of heat so in warmer conditions wine is a lot more likely to oxidize than in colder conditions and in extreme cases we're also using the term mized mized refers to a wine style from madira which is sometimes produced with heat exposure and that accelerates formation of uh compounds such as stalon from oxidation so heat being an important factor there you might have also come across the term primox which is short for premature oxidation most famously from burgundy white wines in the 90s they were really rapidly developing flavors such as brown sugar uh where it was unintended so after like two or three years in a bottle the wine was already turning brown it was already developing all these oxidative nodes and uh in most cases on uh intentionally so this is a quite a complex problem that has is related to a couple of factors so indeed they I identified acidity of one of the factors back then we were already looking at warmer conditions in the vineyard as a result of climate change and then Those Grapes had lower acidities and consequently were a bit less protected against oxygen now other conditions that predisposes uh Primo are leaves so we know that when leaves are stirred a lot then it also predisposes wine to more oxidation and bottle closures once again back in the day in the 90s maybe the corks weren't as high quality as these days and uh primox was a bit more of a problem there even a handful of cases where it was intentionally so for the purposes of wine competitions so some producers want that their young wines show off really well in wine competitions then they might intentionally produce their Wines in such a way that it ages a bit faster so that it performs better at a a slightly younger age okay so I like the distinction between taints and or flavors in the context of wine fold taints are those that contaminate wine they are faults that are not a normal component of wine they're always uh coming from the outside environment whereas an off flavor is actually a normal component in wine but it's unacceptable at certain levels or certain styles for example cork Tain is obviously a taint because it doesn't belong in wine but acetylide is actually present in low levels in all wines and it becomes eable at certain levels but it is a normal component of wine because it's formed during fermentation moving on to sample number four okay the smell of C Bear which also has other descriptives such as cabbage rubbish bin this is a compound called methal Mar captin it's a sulfur compound and it has a lot of unpleasant flavors associated with it so let's have a look at how that is originating in wine and there's two different causes that I want to talk about first one being reduction and reduction is a wine fault that's the result of stressed yeast when I say stressed that yeast is lacking certain nutrients or is otherwise unhappy with its fermentation conditions and under those conditions yeast starts to produce very high levels of sulfur compounds such as that metham or Capon giving all these drains rubbish bin C bear flavors that you're smelling in glass number four particularly yeast might be lacking a nutrient called nitrogen and nitrogen is actually a normal component of grapes it's absorbs from the soil so Roots simply suck nitrogen from the soil and then it ends up in grapes and usually those levels are high enough for yeast to live you can you can think of yeast basically as um I like to draw the comparison with the human diet and compare it with the yeast diet because if imagine I would put you on a sugar diet for a week eat nothing but sugar at the end of the week you would probably still be alive but you wouldn't feel very well and yeast is no different so although sugar is their primary energy source it needs other nut nutrients such as minerals as well as uh amino acids in order to function well and if yeast is lacking nitrogen specifically let me show you where that is trying to get it from so this is a normal wine component called cinee it's an amino acid actually it doesn't have any flavor by itself but as you can see on the bottom part there's some nitrogen that yeast is interested in so what yeast does it will attack this molecule it will B basically break it apart and then the nitrogen frees up yeast is happy because now it has these nutrients but also have a look at the left side of this molecule it has some sulfur so that's the s in there and that frees up it starts to smell of boiled eggs and later it will react to form smells such as C Bear as well as uh as drains all the other smells associated with meth marapsin which you're smelling in in glass number four uh really quite unpleasant in this case a factor that plays a major role here is oxygen and if yeast is lacking oxygen then this problem exacerbates so in other words if there's a lack of nitrogen but also a lack of oxygen then this problem will get much much worse and the Cameron bear smell and all soulfree smells will really increase let me briefly also talk about Light Strike which is the process of wine being affected by sunlight or artificial lights and it has been shown that if wine is packaged into something that doesn't protect against light very well it can also show of more of those sulfur compounds and most famously this happens with clear glass bottles think about some roses or young white wines that can be packaged in clear white glass to show uh show the color of the wine better that doesn't protect against oxygen sorry against light very well and those wines can indeed frequently show smells like C Bear as the result of um of those of of the light interacting with wine components so that's another source another cause of this common bear smell moving on to sample number five the smell of smoke all the descript include clove but also plastic and some people feel that it smells of toothpaste apparently this compound is also an ingred in toothpaste but mostly uh smoke flavor will be Associated uh with this flavor so think about smoked bacon for example smoked cheese smoked paprika or smoked tea smoked whiskey they all have that compound that I added to class number five quo this the result of smoke taint and smoke taint is a fault that occurs as a result of wildfires occurring in the neighborhood of your Vineyard basically the smoke from those wildfires can travel quite long distances and when it reaches the vineyard and blankets all the vines then the smoke Aroma will attach to some components of the grape fine we're talking about stems we're in we're talking about skins specifically of grapes and then when those grapes are used in wine making the smoke flavor will end up in the finished wine and in the face of climate change wildfires are increasingly more common so this is actually a pretty major problem that as a consumer most consumers won't be aware of it but this can lead to huge amounts huge volumes of wine that are unusable because they smell of smoke and they can't be sold at all you will know that some regions have particularly High problems with wildfires we're talking about uh Australia uh California Portugal Chile for example where these fires are increasingly more common and then smoke taint also is a problem with wines from those regions this is mostly a problem in red wines because as you know in red wine making we're using the skins and the Skins are which contain the smoke taint if you're using the pulp only so the flesh only of the grapes in the case of white wine making then the flavor isn't that much of an issue particularly if you're adopting gentle grape handling so imagine you're using techniques such as those used in Champagne we're using whole bunches we're using very gentle pressing that will lead to very little contact between the juice and the skins and then the smoke flavor is basically not a problem so if you're quite careful and you're making white wines out of your grapes you can still use smoke tainted grapes there's a couple of other techniques in existence for example a technique in red wi maker called flash dayon is quite effective against reducing smoke levels in grapes basically you're you're applying a lot of heat in a short space of time that extracts a lot of color from grapes um but also uh removes some of that smoke flavor so that's a way where you can potentially create red wines out of smoke tainted grapes but H it's still tricky you might end up still with some uh so some flavor uh you could also use techniques such as reverse osmosis removing some of the flo smoke flavor but it will also remove other flavors in wine uh I was talking with um an Australian wine educator the other day he told me about the Vintage of 2020 which was particularly affected by smoke Tes so then a lot of grapes were unusable they nevertheless made wine out of it and then they distill it distilled it it and then from that distillation product they made hand sanitizer so 2020 was uh still the co pandemic so then at least the wine could be used to some kind of purpose and apparently at the time when people used hand sanitizer it's still smelled of smoke so it's a pretty persistent aroma so smoke taint uh increasingly uh common flavor problem let me show you a small graph here that highlights some of the levels that you will find guol in so that's the the flavor compounds that uh you find in Sample number five um smoke tainted wies has the highest levels as you can see there's a dotted line which is detection thresold so the minimum quantity that gule must be present before the wine starts to smell of smoke for your reference the wine sample number five that you're trying is also on this plot it's on the far right um so smoke tainted mes can be even worse than this it's also actually a component of barrel-aged wines so that gives of a smoke flavor and um but then if you would see it in Barrel aged wines you will also get flavors such as vanilla and cloves and therefore the smoke will come across as a bit more integrated and less offputting let me go through um a couple of questions here I I already answered this so is this Sul for Tain also with pu fum or other wines wine styles from Flint some so basically this um this question that's that's a great question and the the interaction between soils and wine flavor is quite complex and it's generally believed that there's not really such a thing as flavors being absorbed from the soil that end up in the wine so that is usually not uh not not a thing but in such soils the wine nutrient levels might be a bit lower which causes yeast to produce a bit more reductive sulfur compounds and if you're a good wine maker and you would allow a little bit of reductive compounds in the wine you can get uh such struck match flavors or even mineral flavors from low levels of sulfur compounds but it's more related to this particular uh flavor compounds and it's not one that we will be discussing in this tasting so it's it's quite different from this uh from the Smokey flavor uh and the and the also the reductive flavor number four that we've discussed hope that answers the question um I'm going to move on let's skip this for now let's try sample number six which is the smell of horse blanket from this compound four EP and although horse blanket is the most common descriptor I've got some other descriptors for you as well because not everyone perceives this flavor in the same way so think of sheep's wool as well there's definitely something animal like about this flavor leather band eight as well so there's a medicinal component to this flavor some people feel like they're walking into a hospital when they're smelling this sample and then blue cheese as well so gorgona Stilton will also have this flavor so I hope that you can relate to those descriptors um let me know in the comments as well when you're smelling this wine which of those samples you can relate to mostly this is a flavor derived from bretones and bretan is often abbreviated to Brad so Brad for short it is a wild yeast and when I say wild yeast it's a yeast type that's generally considered an intruder in the winery environment so this is an undesirable type of [Music] yeast now it's easiest to compare this yeast type with the normal yeast type that typically carries out alcoholic fermentation and that ye type is called sacris maybe drinks a bell uh to you and that's the type that is very efficient at turning sugar into alcohol and that's by far the most common yeast type in a production of alcohol so pretty much all wine is going to be produced by that sometimes however Breet andyes can also ferment a little bit of the wine and then only a little bit is already enough to show flavors such as horse blankets what you're smelling in glass number six and it's important to understand the differences between those two yeast types sacris is a type that works very very fast and very efficiently that means that in one or two weeks you can already have your alcoholic fermentation done bretin myis is very slow however so it will never ferment as fast as sacis however it has a superpower it's able to live on very little nutrients you can almost think of these types as Runners where sacris is more like a sprinter and breise is more like a marathon runner so breath is a lot slower but it can sustain on very very little and it can live on for a very long time much longer than sacr mes that tells us that when we are having an ambient fermentation in our wines as opposed to a fermentation as a result of added culture yeast the chances of bream mes co- fermenting is that much higher so that's a major influencing factor in uh whether some wi smell of horse blanket or not let me also quickly describe the difference between red wines and white wines um in terms of bread because it's a lot more likely to occur in R red wines let me tell you why there's uh some differences one of them being acidity and acidity is a lot higher in which means sulfur dioxide is more effective which means these wines are better protected against bread because bread doesn't like sulfur dioxide okay so acidity one of them second skin contact so Breet and mice is able to feed off of some components that are present in the skins of grapes and skin contact always happens with red wines but not all that common with in the case of white wines then Barrel aging another major factor which is a lot more common in Reds than in whites and Brad really likes to hide in a wooden Cask okay it can ferment certain components in the wood that allows it to sustain in wood for a very very long time and just live in there forever until it's is filled with wine and then bread will start to ferment the wine in that CK okay I'm going to I'm going to talk a little bit more about breads but let's uh move on on to the next sample as well sample number seven there's the smell of fomit and all the the scriptors are sweaty socks as well of damp cloth and cheese and this is another component produced by Britain Isis so it doesn't just produce a single flavor molecule it's able to produce more than one and the reason I'm showing two different bread flavors is to tell you that there's not such a thing as a single Breet andyes aroma so it's able to produce these compounds in different proportions and that means that in some wines bread smells more like FID and in others it smells more of horse blanket we know that this is dependent on the grape variety so some varieties show of a different bread Aroma than others and we also know that bread is different in different regions so what I'm saying is in Australia the bread is very different than the one in France for example so there's some genetic differences in different types of breads okay and even within a single flavor we we see that some people perceive it as horse blanket for example comp others as leather so even within a single Flor compound there's quite some individual differences as to how breath is perceived okay and I love these uh the input as well that I'm getting here so blue cheese sheep's wool I think this is still about 40p and then sour crowd combat okay yeah um is that about uh this one the the vomit smell that smells of sour Crow combat I'm quite quite interested in that in the meantime let's talk about how we can avoid bread and maybe you've heard of The Professor Clark Smith he's written a book about uh wine making called called postmodern wine making highly recommend it I'll just put it in in the chat postmodern wine making and he has a lot of very insightful things to say about Brit and mostly that he says that there's two types of uh wineries he says one type of Winery where they know they have Breads and then the other type of Winery where they have breads but they don't know so basically saying that bread is everywhere and it's quite difficult to fully eradicate it in a winery so the advice used to be just be as hygienically as possible and then you won't get any uh get any bread flavor and I think that's still good advice the the hygiene advice but there's more to it he says manage your residual sugar and your yeast nutrients so basically if you have any leftover residual sugar in your wine then it predisposes bread to form even in the bottle so bread can not only form during fermentation or during bowel but also in the bottle and then yeast nutrients we know that if yeast nutrients are too low you risk flavor such as Comm bear from reduction but if you're adding too many yeast nutrients then it predisposes wines to problems such as bread and giving off all these uh horse blanket and form it smells sulfur deoxide again once again really important so that's one of the key things of preventing bread as well okay we know that some wine makers don't mind bread in low levels these are mostly natural wine makers um but also there's there's a couple of famous um famous producers that know that in some vintage they have some bread character and people don't mind it to have the little bit of artisanal character if you like the little bit of barnyard animal vomit and to some extent horse blanket smells as long as the rest of the wine also still shows some aroma so that is not overpowering let's move on to sample number eight the smell of vinegar spider pickles kombucha other script this and people also feel like it has a little bit of that stinging sensation it's almost like someone is in your nose with a feather for example and it's like irritating your nose that's another property of this compound which we call acetic acids which is the main component of volatile acidity and volatile acidity is a problem in wine produced by bacteria so we know that yeasts play a role in bacteria in wine making but bacteria also play an important role specifically these are acetic acid bacteria and they require oxygen to grow note the difference there with lactic acid bacteria that carry out malolactic fermentation Mal uh lactic acid bacteria don't need oxygen but acetic acid bacteria do need oxygen that tells us that when a wine smells of vinegar there's two problems the first one is hygiene and the other one is oxygen exposure and that can be a problem in various stages in wine making as early as in the vineyard for example if you have damaged grapes as a result of maybe Hill or birds or otherwise the the Seal of the grape is broken then that sugar will already start to turn into alcohol and subsequently into acetic acid smelling of vinegar so that already as early as that you can get flavors of vinegar which will make it into the finished wine later for example when we are fermenting and we are using only half filled fermentation vessel vessels that could be another source of that oxygen um that will uh result in higher levels of that V vegar smell cap management is an important moderating factor here as well so if you are regularly punching down the cap of your wine and thereby pushing it into the wine then you're suffocating those bacteria and it will stop producing vinegar smell so that's a pretty effective way of managing vinegar flavors at that stage of wine making also think about Barrel aging uh during Barrel aging there will always be a little bit of wine evaporating from The Cask and that leaves a little bit of space if that is not topped up then you might also get higher vinegar flavors in your wine okay so various sources various places during wine making where this vinegar flavor can develop and I'm going to move on to sample number nine and then uh talk a little bit more about volatile cility that's the smell of nail varnish remover from a compound called ethal acetate for those of you that are tasting along here you can also try to cover the glass with your hand that's a pretty useful technique of picking up any noil varnish remover smells in wine so use the palm of your hand to seal that glass and then swirl for a couple of seconds you could also take a deep breath in and out that's already a couple of seconds and then at the same time you will release your hands and take a long two second Sniff and that really makes that smell of ethyl acetate neish remover a lot stronger some people feel it's more like a a solvent almost fruity and glue is another common descriptor of this particular flavor and we're looking basically at the other side of volatile acidity so when a wine is suffering from volatile acidity you will always get your vegar flavors as well as your nail varnish remover flavors and that can be explained due to how this compound formed it's called it is called ethy acetate which is part of the family of molecues called Esters Esters are always the result of a combination of an alcohol and an acid and in this case the alcohol is ethanol so the main alcohol in wine and the acid is acetic acid that is the vinegar smell that you smelled in glass number eight so when those two compounds combine they will form ethylacetate and that smells of nil varage remover so pretty much in all cases uh these two compounds will be together if wine is suffering from volatile acidity and one stage where I also have mentioned that you can get higher volatile acidity is that of skin contact particularly in whites that um might also lead to some more bacterial growth as well as some oxygen exposure and one of the reasons that some natural wines where often a little bit of skin contacts in introduced can have more of that nil Fage remover smell okay if you are natural wine um folks then you might be able to relate to this to this smell which can indeed happen and of course when a wine bottle is open for too long you're initially getting those oxidation flavors that we've tried such as brown sugar as well as um Roost Apple but then later when bacteria also start playing a role it will start to slowly turn into vinegar so you'll get vinegar and meal varnish remover smells as a result of a bottle that's been opened for too long yeah now the term volatile acidity also means something in chemical terms and so I I'll make the distinction between how we C how we describe volatiles City in terms of flavor and how we describe it in terms of chemical so flavor n Nan remover and vinegar are the two main components of volatile acidity if you're looking it from a chemical point of view I'm just going to show you some some acids here on the right we have malic acid which is a really important acid in wine other ones are for example tartaric acid and these acids are so-called fixed they're not volatile that means that they will always stay in wine they will always stay in the liquid and they can't be smelled okay they can only be picked up on the pallet can only be tasted because they are simply too big the molecules are too large they're too clunky so they will never evaporate they will never volatilize okay on the left is acetic acids so that's called a volatile acid because it's that much smaller look at that molecule at a picture there it's like a lot smaller it's a lot lighter and that means that it can evaporate from wine and then it will start to contribute to smell okay so that's another way of looking volat at volatile City that's more like the chemical way of looking at it and all the acids that can evaporate are called the volatile acids and atic acid being the main one okay hope that clarifies some things let's move on let's uh let's try glass number 10 uh very untypical smell and a bit more of a niche fault but but I thought I would U show it to you anyway it smells of potato skins and some people say it smells of like a darkg soil raw kinoa so kinoa before you boil it as well as the shells of peanuts and this fault is called the ladybird taint and indeed it is caused by ladybird beetles when they are in two high populations in the vineyard this uh does not happen very often but it it's getting a little bit more attention recently also in the face of climate change as ladyb bird Beatles enjoy warmer conditions so let me show you um some relevant photos here on the left that's our lady bird beetle and this problem was first identified in the late 90s in North America um when there was an unusually high population of these beetles in The Vineyards and then they noticed that suddenly all the wine smelled of potato skins and they did some experimentation so they captured some of the Beetles and mated it into wine and yeah maybe not so ethical for The Beetles anyway then that wine was then suddenly showing potato skin flavor so then they proved that okay apparently these beetles they have a flavor impact ladyb bird beetles were first artificially introduced in the United States because they're native to Asia and they feed off an an aid which is the insect you can see in the middle so it was a pretty good idea it's a natural predator of AIDS and they wear a pest at the time they uh feed on soy beans which are pictures on the right now we know that soybeans are typically harvested a lot somewhat earlier than grapes and then all of the ladybird beetles will migrate from the soybean Plantation into the vineyard and that can suddenly lead to somewhat higher levels they've also calculated that about one Beetle per cluster of grapes so that's uh um if if if populations are higher than that then you risk that potato skin flavor in your wine so it's really about the The Beatles actually ending up in the Crush in the winery and then it will give off these flavors obviously the quality minded producers that are hand harvesting and have some some degree of control over selection of grapes they can uh they can remove the Beetles okay uh you'll notice that if if you've uh looked closely here this is actually a pine and if you're a bit more familiar with families of molecules you will know Pines because they're also a common flavor in varieties such as s BL as well as cabinet sov so let me just clarify here about what Pines are they're like a a larger group a larger family of molecules and that can be split into methoxy Pines as well as other Pines and to methoxy Pines there's two two important ones one that smells of green bell pepper so that's the varietal character I was talking about and then the other one which is the potato skin one produced by ladybird beet um but it's useful to know that there's other purines that play a role in wine as well they are formed during the Maya reaction and they produce flavors such as roasted chocolate like very Darkly uh dark chocolate High cocoa Chocolat but most of the times when people talk about Pines they will mean that green bell pepper smell but it's quite useful to know that there's or other Pines that play a role in wine as well okay so let me just summarize what we've gone through this uh this tasting this slide lists all of them um and then to conclude this webinar for those of you that have all all the wines preor in the 11 glasses I have a small exercise to conclude this which can be helpful for identification so if you could please pick up uh glass number two which smells of bruised apple and pick up glass number three brown sugar and then I will ask you to pour one glass into the other like this or a little bit back so both your glasses contain more or less the same amount of wine one of them down if you're smelling this you're smelling Bru apple and brown sugar at the same time and these are both oxidation compounds so this gives a very good example of a wine B that has been opened for too long maybe you can relate to that yes especially white wine that has been opened for too long definitely has this smell moving on please pick up glass number six and glass number seven these are the horse blanket smell and the vomit smell and then pour one into the other and then also pour a little bit back and I smell this which smells of bread so these are our two bread compounds together and that gives a bit more of an authentic like um yeah bit more of a genuine bread smell oh you were uh you're asking me to repeat so if you still have the glasses with you pick up number six and number seven so those are the glass that contain horse blanket and a glass that contain vomit so four EP and ISO valeric acids which are both bread smells and then p for one wine into the other wine so basically we're we're mixing that um form Aroma and the horse blanket Aroma and that gives a bit more of an authentic bread smell so these compounds will occur together when bread has fermented when there's a wild yeast contamination okay perfect finally pick up eight and nine please so pick up the vinegar glass and the nil varnish remover glass and then pour one into the other pour a little bit back these are the two components of volatile acidity combined so these will also occur together there's a bit more of a genuine volatile cility smell okay I'm going to skip this thank you very much for your attendance so in the comment section you will find a pinned message that will link you to the PowerPoint slides if you're interested also to my Instagram Channel if you want to continue learning I have a variety of post on wine flavors there's also my YouTube channel this is where I will upload the recording of This webinar and then I've scheduled another webinar in September about wine white wine flavors so if you like this then you can also link that and uh sign up I will also remind you of that in my newsletter so brilliant thanks a lot I'm going to check if I've missed any questions and I will answer them now since the soil does not influence the wine flavor what are your thoughts on a flavor descriptor minerality so minerality is a really interesting flavor descriptor and it's mostly actually the result of fermentation so yeast will produce a range of sulfur compounds that we pick up on as uh wet Stones gunpowder um Gunflint these sort of descriptors are actually not pulled up from the soil but but they are produced by yeast and that means that wine makers also have some degree of control over it if you're working with very poor soils so soils poor in nutrients yeasts are more likely to produce these flavors and so actually there is some impact of the soil but it's more like an indirect impact it's not as if the flavor is is pulled out from the soil but we know that soil composition has an effect on how the yeast behaves if that makes sense yeah you're most welcome thanks for the nice messages great fantastic you're most welcome and I hope to see you again maybe uh in person at an inperson course or maybe at another webinar so enjoy en the rest of your day cheers