today we're going to talk about crema that beautiful red brown foam this is on top of any well-made espresso we're going to talk about what it is why it exists is it good is it bad should you skim it off should you leave it on all of this and more we shall answer in today's video so let's start with the name because the name is initially kind of confusing crema comes from the Italian fall cream but this is a foam this isn't cream why did it get its name it goes back to 1948 to 1950 Achille Gaggia has got this new espresso machine it's brewing up much much much higher precious than anyone's brewed with before and the espresso coming out of his machine has this weird foam on top and initially people are like what's wrong with the scummy foam on top of your coffee and he turns a negative into a positive he starts to advertise his machines as having crema cafe natural a natural cream coffee or natural coffee cream I don't know this is a wonderful stroke of branding genius in my eyes he names one of the great things about espresso and further cements his reputation or place in history as a father of espresso so the name sticks at no point do we really ever argue it and at some point that Italian word becomes an English word to represent the firm on an espresso so why does it happen why is it unique to espresso what's going on here crema begins in the roasting process when you roast coffee you generate co2 it's a kind of byproduct of some of the reactions that go on inside the coffee bean as it goes Brown things like the male reaction or the striker degradation they produce co2 as a by-product that co2 is trapped inside the coffee bean and if your coffee bean is fresh they'll still be lots and lots inside it when you come to put it in your grinder to make yourself some coffee so you grow your espresso nice and fine you tamp it down put it in and you brew it that hot water comes into your brewing chamber and hits that coffee now one of the properties of water is that the higher the pressure that water is under the more co2 that it can dissolve so that's what's kind of happening here as the waters passing through those grounds at 9 bars of pressure any co2 that's in them that is available is getting dissolved into the water essentially you're kind of forced carbonating you're brewing liquid at this point using the co2 in the ground coffee the moment however that the the coffee leaves the basket and it goes from being in a pressurized environment to an atmospheric environment right there's no more pressure on the coffee anymore well the water has become supersaturated with this gyro too and it can't keep hold of anymore it can't keep it dissolved and so it comes out of solution as a bubble I'll give you a brief visual explanation of this one to hopefully make a bit more sense we're gonna need two things here this not particularly full bottle of espresso this is old espresso it's brewed a little while ago it's got no Chrome on it whatsoever but it is espresso and what I'm going to do is carbonate it I'm gonna sort of mimic the espresso brewing process from that perspective I'm going to force carbonation into the liquid and it'll be done so at high pressure and when we get rid of that pressure well something interesting should happen so the force carbonate I obviously need a tank of co2 or like this one so I'm going to use this I'm going to just push some air out of here because air inhibits carbonation and then so it might not look like it but the excess co2 is dissolved now into the coffee below just like when you're brewing espresso and so when I release the pressure look just like on any soft drink that you might expect a layer of foam has formed now with espresso the carbonation is kind of different it's not as intense as it would be in a soft drink you wouldn't get as bigger coarser bubbles coming out of solution as you would do in espresso the foam in espresso is much much much finer but the principle is really the same which begs the question why does coffee foam in order to explain this very quickly we need to talk about why things foam in the first place generally speaking a firm is a bunch of air bubbles trapped in a liquid and something in that liquid is called a sapphire and a surface-active agent it's something that wraps itself around a bubble of air and it makes that bubble strong now the reason it wraps itself around a bubble of air more often than not is that part of that thing really hates water well the rest of it quite likes water so it's desperate it's sort of repelled by water it's desperate to find anything that isn't water a gas bubble is a wonderful thing because all the bits that hate water can face the gas all the bits that like water can face the water now in espresso at there are a lot of different compounds that are surfactants in fact caffeine at a high enough concentration will act as a surfactant but it isn't really playing a role here there's been a lot of research done on this and broadly speaking they think the active surfactants in espresso are probably things like melanoidins protein derived roasting byproducts there are other things in coffee that do play a role in foaming but there may not be the primary drivers of foaming so that's how we get creamer we've got our espresso you dissolve in the melanoidins some other compounds too co2 gets dissolved in as well leaves the basket co2 can't stand solution appears as a bubble inside the espresso and then gets trapped wrapped up in all these lovely surfactants and made strong as a foam but somehow crema retains more of a mystique than say the head on a pint of beer but they're basically the same thing they've happened for the same reasons but what is it about crema that just gets people so excited now firstly it might be the color chroma looks stunning now the color is tied to a couple of things it's primarily tied to the color of the liquid down below now espresso looks like it's just one very dark brown color but it's not a less extracted or a weaker espresso will produce a less Brown foam stands to reason but it isn't just concentration because roast level also plays a role here the darker you roast coffee the darker the color of that liquid is going to be and therefore the darker the foam is going to be in addition the darker that you roast coffee the more co2 that you produce and it isn't just roast traditionally in Italy row Buster plays role in many as per of lenss now leaving aside the debate or whether we should call it robusta or caffeic an effort will come out of that another time maybe the presence of robusta has been kind of desirable to many Italian Roasters for a long time not just because it's cheap not just because it has low acidity and high body but because it gives you more crema in fact studies suggest that robusta typically has about twice the co2 content after roasting than Arabica which is super interesting but it comes with one more twist robusta typically has less oil less lipids less fats in it than Arabica now you might have made meringue and at some point you might have learned that getting a little bit of egg yolk in your egg white is a no-go for foaming because in that particular foam the fat in the egg yolk provides an alternative to the air bubble for the proteins in the egg white which means you have a much much much less stable foam because there are choices in a way you can go for the fat it can go for the air the same is true kind of in espresso if you're brewing coffee with Arabica chances are your emulsion those little tiny droplets of oil that pressure have emulsified in the liquid below well those oil droplets are actually working against your crema the higher the lipid content of the coffee the less stable the foam is going to be and that's been backed up by quite a lot of research now people will talk about crema as if the emulsified oil in the crema is a really important part of it and what makes it good yes there is a Massa fight oil in the crema but only because there's a mile safai doyle in the espresso liquid and the liquid made the foam it's working against the Kremers lifespan by being there and as a sermo you might then wonder if I paper filtered my espresso if I got rid of the oils my espresso would I have longer lasting crema it's a good question we ran a little test we put two shots side by side one of which had been paper filtered using a narrow pressed filter at the bottom of the basket both of them had nice crema both of the creme has lasted as long as you would want them to and certainly longer than the sort of lifespan in which she would typically want to drink an espresso with in so not worth the extra step from that perspective now one more little aspect that came up a few times in the papers and this goes back to how us Lux's is Tiger flaking or tiger stripes or whatever you want to call that flaking the ill often see on the top of an espresso this is very common when you brew it a lot of different coffees they're typically more of a kind of medium to medium dark or dark roasts very light roasts you won't get as much flaking on there because these flecks are little tiny pieces of coffee they're just tiny particles of ground coffee they've made it through the basket that are stuck in the foam these look beautiful they look really good both you know in the cup and under a microscope - actually they look kind of interesting there as well there is speculation in the scientific community that these tiny pieces of coffee actually helps stabilize the foam it's kind of an interesting idea having read a bunch of papers I'm not necessarily sure I truly understand why that might be the case and I'm not sure that I've seen that in the real world interesting Lee they did note that robusta doesn't really produce that much in terms of kind of Tiger striping or flaking on top which I just thought was an interesting little side note now all of this leads us to what I think is the most important question which is it is crema good is it desirable is it helpful is it necessary before I answer that I want to talk about two other quick things firstly this video has an ad in it and therefore it has a coffee giveaway if you are out of work you've been laid off if you're struggling for money and you can't access great coffee click the link in the description there's a competition I'll pick 10 people randomly anywhere in the world that I can send coffee and I'll send them some coffee if you can't afford coffee right now please continue supporting local businesses they need you now more than ever I do all this because as I said this video has a little ad in it an ad for this video sponsor which is Squarespace if you need a website or a domain that I would recommend using Squarespace I've been using Squarespace for years now and there has made building a website quick and easy there's no steep learning curve here there's no hours and hours and hours spent learning stuff just to get a simple beautiful page on a website start by taking one of their templates and then you very quickly customize it it's your images it's your words it's your personality and it's a great showcase for who you are and what you do online it could be a blog it could be a portfolio of photography it could be an e-commerce store that you've started out of your bedroom it could be a showcase for your cafe or your restaurant using Squarespace makes all of that quick and easy there's nothing to patch upgrade or worry about and if you have an issue there's 24/7 email support but just give it a try Sona put the link down below and build a website and after 14 days when you're ready to launch use coach James Hoffman for 10% off any website or domain thanks to Squarespace for sponsoring this video I will put a lot of links to different scientific papers up on my particular website there'll be a link in the description to that particular page if you want to get deeper into the science there's one particular paper I would recommend strongly as a starting point and I'll put in a few little supplemental references that you might find interesting too but let's talk about is crema good and from a scientific perspective it's interesting it's not as clear-cut as you might think now crema is a great piece of feedback it says you probably brewed the espresso pretty well it doesn't say if the coffee was good or bad if it was well roasted or badly roasted but it says you brewed fresh coffee slow enough to produce a good dense foam you've done okay or you can think about another way if you brochure that doesn't have good crema someing has definitely gone wrong but does it really enhance this sensory experience and here it's interesting because broadly speaking the answer is kind of but no now years ago I got myself in trouble with the internet for advocating skimming off the crema for an espresso it wasn't even my idea it had come from the coffee collective in Denmark you've been doing it for Americanos I did it with an espresso and was astounded by the difference that it made try it for yourself brewing espresso get a couple teaspoons and skim off a layer of crema stir and drink of the shot and you'll find a substantial reduction in the bitterness and kind of roasty quality of that espresso it might also be lacking and you might argue that it's more effort that it's worth and life is fine you can just stir and drink your espresso and you can have a nice time and I won't argue with you there but this has been backed up by proper research too there was a paper published by a doctor performer and others I think she talked about it in a RICO talk that sort of said that varying the amount of crema essentially varied the presence of the roasted note I think was their language they kind of rose essentially of the coffee more crema gave a more intense kind of a roasty quality to it now that paper did also talk about how it's a perception of very top-level flighty aromatics varied with different levels of crema essentially they were more perceptible with more crema but did also say that broadly speaking from a sensory perspective there were not strong differences in the taste profiles of the espresso based on how much firm they had outside of this roasted note that really varied across all of them for me skimming espresso massively reduces the bitterness and I think in part because all of those fine pieces of ground coffee that are trapped in the foam well they get whipped out and taken away and you don't have to taste them if you've ever ended up with any amount of grounds in your mouth for whatever reason you know that they're not a fun time we enjoy we taste with more than just our mouth on our noses how things look has an impact and a great looking crema does enhance the joy the pleasure of espresso even if it doesn't do it in a kind of objective way I'd like to think chroma plays a role in the kind of tactile aspect but I'm not sure in a blindfold if I could tell the difference between one that had lots of crema and one that kind of didn't the texture of espresso primarily comes from the concentration of the liquid as well as the particular compounds that you've dissolved which is kind of down to the coffee that you started with now I did wonder if you could actually cheat and get more crema somehow so I did Triforce carbonating coffee beans essentially I put a bunch of coffee beans in a bottle squeezed out as much air as I could and then aggressively carbonated them didn't really seem to make any difference even if I held it under pressure for a little while so in case you're curious I tried it for you not the biggest result such as life so a quick summary a replica produces less crema than our Buster but darker roasts produce more crema than lighter roasts fresher coffee will give you more crema the color of crema is about how dark the roast was to start with and how strong the espresso that you've made is and that's kind of it crema is beautiful but you don't need to chase it you don't need to worry about it eking out a little bit more may not necessarily give you better tasting coffee I've adjusted to hear your thoughts though what didn't we discuss what should we have talked about that we didn't did you go down a rabbit hole of chasing as much crime as he possibly could and then find that things maybe don't taste as good as they could let me know your thoughts down in the comments below but for now I'll say thank you so much for watching I hope you have a great day lots of you have been asking about the French press poster it's now available we worked with an incredible artist Ashley Al and a strand twist and she's done a beautiful job she even put me in here as well as a few of her friends I think which is kind of cool so you can check that out now it's available link down the description below it's available for a limited time hope you like it [Music]