Well Tom that's me. I've got a six professor. Yeah Georgia. Better to have you here for the third squishy physics. Which as you probably know it's one of the all with chocolate. So I want to tell you a little bit about the science and physics of chocolate. But before that I want to thank some of the people that have actually made these possible or have contributed to a very large extent and I want to start by thanking the school of physics. Right. And in particular Eckstein. Also I'm thankful to Dr a brake on me. Sally from the rain very much. They've been helping throughout every single detail that organizing something like this requires. I'm also thankful to the College of Science and I'm one I think well for our being professional for both Burke he's been support these are supporting these events from the very beginning. Janet Zebul the graphic designer and colleague of signs us help with the posters on the Flyers all worth anchor and we thank her for that. Also on faculty the office of the Provost actually for their GED fire program and. Kind of our fire type of grants right to do sort of new things and they are sponsoring the creation of laboratories that are going to allow to bring squishy physics training to the undergraduate and graduate education at Georgia Tech. So I'm very thankful for that support. Mr HOAR have he's been also very enthusiastically supporting these events in the very beginning he said the director of favor manufacturing of the Coca-Cola company. Dr Conrad who sitting right here and she's also been very supportive from the beginning we have a Georgia Tech nurse the Materials Research Science and Engineering Center that we have here at Georgia Tech. And then we have two new sponsors that I like to work on these year does really well you are on the Institute for bio science and by engineering at Georgia Tech. Finally but not for that belief that. Very thankful to the firm on Science Center. They are the main organizers of the squishy physics photography contest and in particular I'm very thankful to the director Mr Douglas Robbie and also to Mr Tony made it. So thank you to all of you. It's because of you that you know to a great measure. We're here today. All right so without any further dilation let me just announce the winner of the photography contest or we have two winners each year are both fast six graders right so the first prize goes to unleash Kumar from Fort Hills Middle School and the second prize of all tools the giant from Shadow mentary so come and see me at the end of the event will give you the diplomas and will range how to get you the track associated to your prices so congratulations. OK and then let me introduce you. The the stars of the first question of physics are today physics professor Arjun year old from the University of Pennsylvania and William Yosef from the White House. So I like to start with a chap he often he's a bachelor in arts from University of Toledo he's master in art from Rutgers University. He's double A Yes the green from New York City College of Technology and throughout the time he actually worked with known very famous chefs the blue and Thomas Keller then he went and began using the pen a career and he operated at the pastry Parminter Tavern on the Green restaurant in New York City. He served at this as a pastry chef a munch are a restaurant in New York City also and finally he planned on the sign and opened the pastry department on the restaurant and bakery two thousand and seven. He's the executive pastry chef at the White House and he's actually contributed an interesting book that I strongly recommend the search for Dummies was published in one thousand nine hundred seventy. Recently Perhaps you've actually read up. Already in the news. He announced that he's leaving the White House in the coming June. So he's a fantastic person and he said willing to give up such a job to actually initiate some sort of educational activities in trying to bring people to hear it healthier. So as he was saying the other day you can actually have a highly delicious food and that should be an objective frame but at the same time you. You can have healthy food. So in addition of weaning the leashes. You should also eat healthy. So that's a new endeavor that he actually had undertaken in the past and he's going to return to the physics professor that we're having today is hard. You know so Arjun obtained his bachelor's in science from Cornell University Ph D. from Harvard University and then he to postdocs our Bell Labs one of them we Nobel Prize winner. Steven Chu He then joined the University of Pennsylvania. That was in one thousand nine hundred eighty two and he's been there since then he's actually educated or graduated more than thirty graduate students through all these time. And he's contributing contributed around three hundred papers many of them that have very high impact and that has been very influential work once all his current position. It's associated mainly with the part of the physics where he's a professor of science and he's also the director of the center funded by the National Science Foundation and he says research interests broadly protein condensed matter but in what we call soft condensed matter because you're dealing with materials that are squishy and easy to be form right and it turns out that he's also very interested since the very beginning optical sciences and he's dedicated part of his career to use up the X. to understand Biomedical Problems. So what are we going to hear about today. So we want to start with Arjan. Is when I tell us about some of the chopper fundamentals and I tell us the experience more or less what Chuck ladies some of you may know about I'm sure some of you may not and some of you may or some of you. I know but there are plenty of surprises when you actually think about truckler So in terms of any concrete slicing sixty from Ford for example there's only one of them that we like as a costumer So when you each outlet. You will actually enjoy the most any one of these for six weeks. So we went up quite a bit of our faces on face transitions and how you go from one face to another from one crystal to another crystal phaser from a crystal to a liquid face. I'm interesting liaison I illustrate all of these with some of his research. So he does. Beauty for experiments you see not the gun microscopy. Where he images little particles are Gielen around with the thermal motion. We call them call it right there to some extent like a knot on my saw the mini classes you can think of as classical objects that if you think of an atom Classically there remain a simple bam. So they geve all on the crystallize and they do things like the atoms do. So he uses these to learn about physics right in general and condensed matter in particular and then he also tell us about emotions. Which as it turns out it's a way a very interesting way to try and mix substances that naturally will never means OK. And then the chaff air will take over right and he's going to do some magic. Well after though no not really matter exactly level physics for exactly when I was some experiments is going to cook something and hopefully you know you get the perception that physics. It's everywhere. And so he actually made there two or three research so it made actual playground Ashworth use novel ingredients on the whole saw plainly to be with the texture whether they're stiffer or softer and then he's also going to make a forms of these is something that looks like a solid body sets intially compost over. So it's pretty intriguing and so you'll see that in action. So I hope that you will enjoy my event. And I hope that you were inspired by the event also I hope that you will get the feeling that many of us have that physics is about explaining nature and natural phenomena. Not necessarily only thinking about electrons or atoms or quantum mechanics finance essentially about everything on food and cooking and you know food transformations are no exception. So I really hope that you'll be inspired by the event and that you'll start thinking about the physical properties. And those transformations that he was when you cook that I'd like to welcome the speakers of the Saturday. Thank. Well thank you. Wilbur to for. Putting this event together and for inviting me. And I know that you're all here really to see Bill. But you know my favorite subject I'm going to tell you about my goal today is just to tell you about my favorite subject which is physics. And in particular I'm going to you know tell you about phenomena in soft matter physics or squishy physics and some of the brushstrokes I think you'll see will overlap with some things about chocolate and so. What my plan then is I'm going to disk give a little background on chocolate to kind of set up some of the things that I'll talk about and hopefully come back to at the end and but my main you know the main goal here is is this is to you know talk about matter phases phase transitions and. I want to just not just tell you about the phenomena which you might read about in a book or something like battery of it. Basically I want to convince you a little bit that this is these are questions we're still thinking about in physics. Right. Would we don't really understand them all that well and I'll show you some little tidbits of stuff that we've been able to understand in our lab in the soft matter side and then we'll go back and I'll talk about again. Alberto already has. Told you the chocolate has six. I think different solid phases one of which we like and so I'll sort of come back to that a little bit and then I'll talk about how do you mix mix stuff together doesn't like to mix together. OK So first to you know certainly even though I like physics a lot. I also like chocolate and this is sort of a world map showing sort of where it's grown is really in the temperate climate here and the trade routes from there to places which eventually get to us. And so this is something that sort of worldwide importance in interest and it starts. If you like with this tree of the cocoa tree and if you look in the tree see that there's these pods and if you cut open the pod you'll see that there's these kind of beans. And basically the first thing they do is they take out the beans and they ferment them and actually there is a huge amount of science of physics and biology and chemistry and metabolic your shoes having to do with fermentation which I will say nothing about. Then they drive them and then they grind them again there's all sorts of interesting things to try to understand people do that in the good physics and chemical engineering about sort of the mechanic Ryall A-G. of the mechanical forces in the response to mechanical forces in volved and in something like this which again I will not talk about. And then at the end of the day you get sort of well there's you know there's all sorts of different kinds of chocolates but the main three things I'm going to focus on today which are the main three if you get one of these seventy five percent chocolate bars. You can go to Trader Joe's or something and get that it basically has you know sugar which is really added. That's not from the cocoa bean and. And it has cocoa butter which is essentially the background. You know but that takes up most of the space in the chocolate. And then there's the cocoa nibs which you keep brining up and that gives a lot of the flavor of the chocolate and I want to you know you take these things and you mix them together and you feed him up and you cool him down and so on and you make it make it make a chocolate bill so you stuff like that. But you know you have to mix these together and so you know I want to tell you a little bit about how you do that and just again as if you just sort of point out a couple of things the sugar basically is something that's what's called Polar right and so that polar just has to do with how the electric charge is distributed really in the molecules that make up the sugar but the bottom line of it is that it likes to be water. The cocoa butter though is not polar OK so it doesn't like the water and then the cocoa nibs. They're complicated but there tend to be a little bit more polar the non-polar and somehow you've got to mix all these things together right. And so. What is probably there is some most people here know what's sort of when you think about mixing two things that don't like to mix what do you think about oil and water right so we have to fix sort of so solve that problem. The oil and water problem. So I'll say something about that and then again just to remind to reiterate that cocoa butter is playing a key role. It's the SOL it's sort of filling up most of the space. Again it depends on which kind of chocolate you're talking about but often it is and it's even Lee dispersing these chocolate nibs in the sugar and then the nice thing of course is that you can hold it. You know you can snap it at room temperature. But when you put it in your mouth it melts which is a nice thing about chocolate. So we'll talk about then in connection of that crystal phases and the surfactants. OK So let's let's talk about matter in fees. So first of all again. Bases matter you're you're familiar with an every day life was the most probably the most common one is use of water right so in the gas phase it's steam in the solid phase it's ice and then you can have the fluid liquid face. Lots of materials have different phases. I mean so here's gallium. Right. Gallium it turns out is. You know roughly your body temperature can melt and so. So this you know this problem about having faces and making transitions from one phase to another is sort of a ubiquitous problem in physics that we try to understand. And certainly you know and then that and I want to sort of at least give you a sort of a way that I can think about understanding that in a simple context. OK So one of the so the first thing I should say that you want to do business is often do is try to figure out what what things are made of. Then you've tried to understand the properties and try to make a connection between how they're put together in the properties and then and then you can answer questions about how does it transform from one kind of phase to another for example but so if you look at the building blocks of matter right in anything like ice if you take ice and you just sort of magnify it and magnify it and magnify it what you find in the end is that it's sort of made up of one sort of elemental unit which is the water molecule right which is oxygen and hydrogen and I mean you can go further down right. You know if you if you looked at the oxygen. Right. It's got electrons it's got protons it's good neutrons. But for most of the sort of. Every day chemistry stuff is so the soci with food and for many things really this is sort of the end. Elemental building block and that's what I'm going to. I'm not going to worry too much about the stuff that's inside the atoms. OK So you know this is what happens when you sort of magnify down with with water. You know you can do the same thing for table salt. Right. And if you did that what you'd find at the end of the day is that you have sodium atoms and chlorine atoms arranged in a well defined way and some kind of a pattern in three dimensions. And you know even if you look at cocoa butter. It's a lot more complicated bollock you'll But you know you can break it down and in fact sometimes there's often more than one kind of molecule. But roughly speaking you get sort of a relatively it's still there sort of a molecular building block that looks kind of like this. This is kind of a model of it. It's got three tails the tails could be all pointing backwards. Often the you can have one pointing one way into pointing the other way to kind of a Y.. And but you know so this is kind of the fundamental pilling block of cocoa butter and it's made out of carbon and oxygen and hydrogen. And. I'm going to you know in understanding you know phase transitions. I'm going to do something that here the physicists often do in this just simplify this. OK So you know these are complicated or relatively complicated molecules especially the cocoa butter but I'm going to sort of imagine then I'm going to think of all of these as just a sphere or a particle. OK And what I want to try to understand is if I if I you know what properties of this particle. Does it. What properties does this particle have to have in order to sort of have a possibility that it could have a solid phase and a liquid fifty's. OK And so. And it turns out actually that this approach actually works very well to understand many things and there's sort of a few things. They get you along a few properties about this these these don't think of them totally as like billiard balls right. They could mush into each other they could sort of overlap. But basically these properties that you can attribute there are a couple of them are enough to understand why you might have the. These different phases and so this is sort of my most probably my most complicated slide but basically so I just want to talk about what are the properties that generally these particles would have. OK And this is true then of these cocoa butter molecules at some level of the of the water molecules. And so on. And so on the left hand side just focus on that first basically just the main thing is that when they're far apart they don't feel each other. OK. So you don't really you know one can be moving this way one to be moving this way they don't affect each other's motion. And then when they're very close. They feel each other very strongly and they want to repel each other. OK So this is like this arrow is like a force vector. Right. So if they're pushing they're being pushed apart when they get too close. And then there's there's usually a scale at which they. It's like the bear story of the Three Bears of in-group. I forget the name of the story but basically the Goldilocks total Goldilocks in the three very you know basically you know the this is too far apart this is too close. This one's just right so there's this one distance where generally you can find for many molecules most typically that there's a distance where they like to sit apart. Yeah that's a good analogy you know right. Now so on the right hand side. I'm sort of just restating this but in a kind of a diagram people often use having to do with energy. OK So just this dash line here would correspond to zero energy if you like and this is for hydrogen but it could be for anything and my ball right. And this this axis here is just the distance they are apart. So over here they're far apart. Right. And basically they have it doesn't cost any energy to be far apart. You don't even know each other. So they're over here. They're too close. So it costs a lot of energy. This is positive and they want to go down the hill. Into this little well here which is where they do look which is just right. It's a sweet spot where they want to sit and so different and you know generally most molecules have this kind of. Three features and you know what. What can matter. You know is one of the important things that can matter is how big is this this sweet spot how energetically how low is it compared to zero because you know it's that's what's binding. It's the binding it. OK And so just now I want you to keep that in mind. OK So this is what I would call this is sort of sort of associated with the energy of this of the of the system and it has to do with how far they are apart. OK So given that you know can we understand the phases of matter let me just remind you about the phases. You know most of the time you think about three phases liquids and solids and gas is right and so in the solid case right. I'm telling you this and you'll have to take my word for it but basically right these are basically these these these particles that we've made some of these molecules are sitting on some order to Ray and you know a solid Of course it has a well defined volume and it doesn't change its shape unless you push on it pretty hard. A liquid is has roughly the same density actually usually as the solids. But it's disorder. And so you know if you put it into a container it'll sort of take it'll have a well defined voluble take the shape of the container it contains shape easily and then the gas of course is just very the atoms are very far apart like in the scene. And so if you put it into a container it will expand to fill up the fill up the container. So those are the three phases and the sort of can we understand why we get them in the context of that little model of particle interactions and the answer is you kind of can you just need to sort of want to add in one important. Idea and that has to do with temperature. OK So temper. Basically it's like a kind of a measure of it's random the random. Jiggling this. If you like of the particles. And so you know at low temperatures. You have a you know relatively little amount that you're shaking at higher temperatures you have a relatively higher amount that you're jiggling around. And so if you think about it when you go to a low enough temperature. You can get stuck in that sweet spot and you don't have enough jiggling energy to get out of the sweet spot. So they sort of sit there roughly at that sweet spot in this crystal then if you get a little bit higher in temperature jiggles a little bit enough enough so that it can get out of that little sweet spot it can get out of that little well it doesn't really escape that far from each other. It sort of knows that that was there but sort of it becomes disorder. OK so so so that you can kind of see and then of course you know if you go to higher and higher it's easier to get away. And so you know so that so you have this. Potential energy of interaction between the atoms that's important to the particles that's important and you have this other thing. Due to temperature causing them to shake randomly and it's a competition between those two things that determines whether you make a phase or not. And you can be a little bit more precise and I just want to introduce one other term which don't worry I won't use that much again but it's kind of a cool thing which is called entropy. OK And that's a. It's a it's a quantity it's something that you can measure about these systems it has to do with it's disorder. And in the Second Law of Thermodynamics sort of says things tend to become disordered. If you know if I saluted and left to their own they're the evolved to having the maximum entropy or the maximum disorder. So in terms of figuring out what phases forms. It turns out that there's something called a free energy which is basically a competition between this internal energy having to do with whether in those sweet spots in the well there or not. And this entropy term which depends on temperature. OK which is sort of a disorder. Systems. So again at low temperature you have a typically and most distant. You have the you is big because you're all sitting in the wells. And the entropy is low. Because it's ordered. OK And as you go higher in temperature the sort of trading off order. If you like an energy. For disorder and entropy. And so if you want to calculate what phases before you can start with a microscopic model of your system and you can in principle try to come up with the systems that have the lowest free energy at any given temperature. So that's something that is going on in our community. OK so yeah. So that's sort of what I wanted to say by way of background. And then I just I did want to before I show you some of our some some a few results from our lab just just to remind you again that these problems even though they might seem like they're solved because often people tell them to you like there's all there and they're not. OK There's lots of questions what kinds I took he told you about solid clicks and gases are there other phases they could exist. How are they similar or dissimilar. If you have a crystal I'll show you something about this. Where does it start when you melt it. How does it start melting does it start melting from the surface to start melting uniformly throughout it is there a way that I could control that if I want to make a crystal certainly in chocolate you want to make the right Crystal Wright. Actually it's much harder in a way because there are five different kinds of crystals you could make your six different kinds of crystals. But what one of the things that you can do to try to make a good person. What happens if you cool to fans and tails. So I'll say a little bit about these things these are still questions that are not understood. Well OK so our lab like Alberto's Actually we do experiments in soft matter and one of the one of the fun systems that we work with there are basically particles in water. OK so these could be plastic particles. These could be the last part. Because these could be Paula. Fancier particles made out of polymers that can change size and so but basically we put them in water and then we pack them really tightly and we we can make essentially thermodynamic systems equilibrium systems which behave in many many ways like like water like ice. OK I skewing to liquid water and so on and we can see the good thing about these systems is I can change their shapes I can change their sizes I can change their interactions even but I can watch them generally in the microscope. So I can see what's happening to all the atoms which is generally a hard thing to see. OK so what we're going to do is I'm going to take stuff like this these kinds of particles. You know maybe different shapes I'll start with the spheres though and put them into a sample cell. You know it might be pretty thin and you know the particle might be about a micron or maybe even an animator you know a few few hundred metres. And but I'm putting it into a cell that might be one hundred fifty microns thick. So there are lots of layers it's a big book system. I'm going to show you pictures mostly there to be pictures. That's just one slice you'll just have to get the idea from that but you know also use some movies where we're scanning through and so you'll get the sense that it's three D. and then basically we were a bit. What we do is we just sort of mix these things together to change a little condition look at what happens. And so again this is this is the kind of two dimensional slice you might get when you take these micron sized particles and you pack them. Fairly tightly. That's a slice in the sample. So you can see all the little particles. Many of them. OK so. I talked about crystals they talk about liquids Here's basically we took those particles we put them into these cells. Here's some pictures of them at different temperatures. You can see. The low temperature it's basically ordered and they're moving a little bit. This is a crystal. Then I got a little bit higher temperature and still Crystal and actually if you look at it. They're all ordered they're sort of hexagonal e. Symmetric and then but they're jiggling a lot more right. And then I raise the temperature a little bit higher. You have a coexistence between the crystal phase. That's ordered here but you're going strongly in a liquid phase. OK so here's sort of taking this soft matter system of particles in water and sort of mimicking if you like the crystal to fluid formation. So that sort of going from a crystal to a liquid you can also go the other way you can start in the liquid and this is of course something that's important for chocolate start in the liquid phase and then get to the solved. OK Also a little bit about that. Again but in that case by lowering the temperatures. OK so. So one problem that we work done and other people have work done. Certainly is to try to understand when you have a melting event where does it begin. OK. In so we made these crystals of particles. Let me just show you one. This is a crystal. This is looking at it in a microscope this movie is just scanning the image plane so you can see you can see that there's all these particles that you know they're sort of. Like those little spiritual spots they're ordered but I hope you also saw that if I had as I scanned through it wasn't just a perfect crystal there was defects right there were stacking these are called stacking defects. There's a defect there. You know it still looks like a crystal it's still kind of crystal in for sure but it's not it's not like everything is perfectly arranged. OK. And so if you. You know here's an example of one that we've sort of had a lot of fun with. This is called a defect it's called a green boundary. So you can see this is again this is a slice. But over here you have an ordered crystal over here it's ordered but their orientation is rotated. OK And the rotation of the orientation is is across this thing here called the Green boundary. OK so a green boundary is a kind of a defect it makes it something that in this crystal that makes it different from being perfect and sort of we had this idea and actually other people had this idea too. We were able to do the experiment that. The atoms basically near the green boundary they're not really exactly where they want to be OK And so if you like they're not perfectly in those wells that. And so basically if you're going to start melting that's a good place to start because they're not energetically in their lowest states. And so we didn't experiment where we basically took we found a green boundary in these crystals and we looked to see that it indeed start to melt there and it just melt everywhere. OK so it could have been were sort of My guess is that it would start to melt around here but it could also just be melting over here. OK. And so here's these are these are movies. Showing this is that lowered low temperature where it's still solid completely. And this green boundary you can see here as I'm scanning through the sample. I'll do it again. It's actually you have to sort of spend a lot of time staring at this. But you know you have to take my word and actually I didn't really do it my grad students did but basically basically you can convince yourself it's a pretty sharp interface and it's a solid solid interface and it's basically the same crystal and solid but different orientations of the crystal. Then if you go a little bit higher in temperature and you stare at this a long time. You can think well maybe there is a little bit of disorder not just disorder but a liquid like behavior along these the screen countering so I'll just look at it again and again I. Expect that you could tell that necessarily but you can certainly tell it here. OK. So here you can see well we've got these two crystals over here and it's really started to melt in the middle. OK So this is basically the kind of thing that we were trying to see if we could understand and you know if you keep raising the temperature then that region keeps growing until eventually it and follows the the system. OK And you know I don't want to you know so we saw this one effect. We were able to learn about it because he looked at it very carefully and then there's like about one hundred million other things to try to understand you know if this is a bowl Crystal how does that differ if it was a thin film. OK this is going from a liquid to a solid. Well what is the similar kind of physics going from a solid to a solid OK and so on. Another thing is that talking here about going from a crystal to a liquid What if we want to go from a liquid to a crystal. OK how do we do that when we know right. You know certainly if you have a liquid and you want to make ice or something you lower the temperature. But it turns out right. If you want to make a really good crystal. Like this. OK so if you look at this. There's it's not perfect but it's pretty good. I made this by doing it very very slowly. OK cooling it very very slowly. So all the atoms if you like have time to find their lowest energy state and they can move a little bit in and so on. Now if I did that fast. Then you wouldn't get all these liquid atoms that were initially in these disordered positions don't have time to move and so they get they get jammed. If you like and you make a disordered structure which is the glass. OK. And the glass has a lot different properties than a crystal generally. And even for this these different phases of chocolate if you if you if you make it with a glassy if you cool it too fast then basically you can make something that's not very good. OK So this is something again to disk even mind as we go when we go back and talk about chocolate The other thing I just wanted to say because it's so amazing to me every time I think about it is that you know I've made you. Hopefully think that those complicated molecules are spheres. OK. And spheres with just this little little property that they like to be close together. OK. At a certain special place. But what if I just change the shape. Right. Certainly those molecules have different shapes. What if I just you know the nice thing I'm thought matter is you can sort of have these objects and you can literally change the shape and look at what happens is still a term of damage. So suppose that I changed it from a basically a sphere to Iran. All right. You know you could still imagine that the rod could have or could have arbitrary positions like in in a liquid you could have arbitrary orientations. So you could still get liquids and gases and solids in principle but you know let me just ask you I mean do you think that's all you'll get no right. Good I guess I set that up. Well for you and I have to think of a better way to set it up but OK so there's a very you know. So so the answer is. That's right. There's there are the faces or some of them are the same but lots of them are different so for example you know liquid crystals which are basically the molecules used in your displays of almost everything right there. Basically they're not they're not these big particles but they're on a molecular level they're like little rods. OK And so. It turns out that if you pack them tightly. But not so tightly to make a solid you can make something in between a solid in a liquid. So this is basically what I mean this is called in the manic phase and the the rods are basically they're just ordered in position but they're all generally pointing in roughly the same direction. So this is this is a sort of an orientation of the ordered. And that's sort of the most famous thing about the crystals and this is sort of the phase that's really heavily used in these displays because you can you can manipulate light. That's traveling through medias where you have all the molecules lined up in one direction. You can manipulate basically the polarization of light by switching the direct OK with an electric field. So. But not only that. OK So this is the regular kind of a liquid This is an ordered liquid. But if you actually you know this is very rich and I just want to emphasize that if we take rods we can start with this regular liquid and then we can make a liquid kind of where there are there are layers. There all generally oriented in one direction but there's kind of a layering OK So there's kind of a one dimensional order this way. You can even have the layers with their tilted OK it's instead of a rod like molecule you have a plate like molecule you get all sorts of other interesting phases like you can get these poker chip stacks right. And this is really a lot of fun to figure out what are the phases and there are many surprises and there are many interesting things about this. And so you know we actually started to try to do some work in there where to does a lot of work with this to try to sort of make some liquid crystal systems that we can look at in the microscope. And so to do that we made a rod this right is a dead F. T. virus. So it's about a micron long one hundred enemy and it's pretty narrow pretty pretty pretty and its diameter is pretty small. So it is very much like a rock and then we just take these rods and we put them in the water and we had a polymer and we change their concentrations and change the temperature and you know these are the I'm not going to explain much except to show you these are pictures of the kinds of things that we saw right. So these this is a cartoon of that sort of one layered that layered one dimensionally ordered material. Right. And this is this is this is the this is the actual image from the microscope this is the cartoon of it. These. The rods right there. You get a sort of a sheet of it then you get some polymer another sheet polymer Here's a defect actually when the sheets come together and sort of to go into one. And so on and then you can raise the temperature and you can melt these things you melt these these layered structures into this so-called nomadic structures these orientation of the order structures and so on. You can even make droplets of that. Here's a movie of the droplets you can. So this is a droplet that starts as a layered structure and just raising the temperature and it's changing shape because it's changing from a layered structure into that orientation toward a liquid I'm melting the sort of one dimensional solid into a liquid. OK so you can imagine that this is crazy fun and that's you know again that's something that we do. OK so now I want to go back. And I'm not an expert in chocolate really but I'm just going to try to sort of show you some of the areas where there were some overlap in these ideas. And I want to talk at the end of course but the mixing. OK So again just to remind you. This cocoa butter which you can think of as the kind of background phase in which everything is put into. So the sugar crystals are going to be put into it. These chocolate nibs are part trumpet particles are going to be put into it the cocoa butter basically looks like this it's this big you know it's got these three chains hydrocarbon chains and they make kind of like a Y.. OK So you know I've asked you to think about spheres I told you a little bit about rods. You know you think that you could make I mean I wouldn't necessarily even think I could make a crystal with this and it's kind of a weird object. But the answer is you really can't. And so you know you can't just unfortunately there's a molecular size. So you can't really just look at them under the microscope and figure out what what the what they what they are you have to do things like a very common trick is to do with called X. ray diffraction. And you can. So you take X. rays you scattered off these samples and you look at the pattern of spots that come off and then you work backwards like they did for D.N.A. to figure out what's the what's the crystal structure inside. I just want to emphasize that just one thing so you here's just two different ways that you could have packed these wives right. So this would be one crystal type in which you could see the red just look at the red right. The red and then there's a black line and there's a red Y.. But here they're all three in a row right. So this is a different structure and because of it's a different structure it might have different properties in it if it's a it's energetically likes to be in that position more might be harder to break the heart might have a different melting point. So all sorts of things. Also they're not all that different. So you can think that well you might be if you're not careful you might get both of these kinds of structures forming at the same time in your. In your material. OK And that's in fact what can often happen. So here's here's the different faces of cocoa butter and you know this is sort of giving the temperatures that they like to live at and you know many certainly most of these these faces here are kind of crumbly there they don't like you know people don't like them very much. This one. Here's the good one five. OK So people want to get five. OK that one has this nice shiny appearance snaps and it melts in your mouth. OK so how can you get this. I think I think Bill is going to show you something about this. But let me just show you something to OK So it's kind of tricky and actually this whole business of making good crystals is tricky. And that's so that occupies a lot of people's time for not just these kinds of crystals but for protein crystals because you want to figure out the structure of the proteins lots of things. So here if I start this is what I'm planning here is temperature and i'm time. OK so I'm putting the chalk. Put in a pan and heat it up and it's usually very common you heat it into if you want to sort of. You want to you start in the liquid phase you heat it up into the liquid phase and then you call it down and here's just two different things that people do they let it cool down right into that. Good good sweet spot to make this phase five usually that doesn't work all that well and so people what they would do is to add in little they have from somewhere else. They have these little crystal lights of the right shape and size of the right face and they just dropped a few of them in and those that like nucleation sites where you can grow the right shape to kind of crystal. And so that's a common thing that's done. Another thing and I guess that's more recent that people are doing that. According to Bill. The other thing was that you can you can actually cool it down lower So as you cool over here you'll get a little bit of this phase and a little bit in the other phases and then you slowly go back up melting the other ones when you have the you have the good one that you like around and then you can get that one to sort of dominate the other ones and you can get mostly one kind of things. So this is one interesting thing this whole thing I think is called Temp tempering. And certainly it's more complicated with the five solid phases than it was for going from the liquid to the solid but. It's a similar set of ideas that one has to apply. OK then the other one just to remind you has to do with how to mix the different parts of the chocolate. And you know again you know that if you have oil and water. They don't mix. You can actually get them to kind of disperse if you shake it really hard right. And you can get these bubbles forming of oil say in water but then if you wait a little while. Bill coalesce and they will go back it will go back to this. OK So somehow you want to make this shake it and make these bubbles. If you like and but have them stay. OK. So to do that. You really need this sort of magic molecule. OK Which really is kind of amazing lein useful. It's called a surfactant and it's a molecule and here's one of them an example of one but the main thing conceptually is that they have one side of it called the head. Usually it likes water. OK so that's hydrophilic it's Kong and then there's this tail that's like oil like soil. It's a hydrocarbon tail and so if you think about well what will this do if I have oil and water even just in water will do and actually does all sorts of interesting things but just to first off if I have an interface between water and oil. Then these molecules will go to this interface because that way they can keep their head which likes water and water. And they can keep their tail which likes in oil or it likes air better than water too. And so on and that's energetically lower lower rates energetically favorable so. But there's all sorts of other things I just want to mention that these thing these molecules can do so we just had water. If you crank up the concentration of these of these molecules you get what's called a myself. OK So this is a little object where the outside of it. It's a spiritual object the outside of it is near the water where it likes and the inside is this tail soily you can get sheets. OK this is you know your cell membranes like this right where the outsides like the water in the insides like you can put proteins in there and stuff like that you can get vessels. Right. These are satirical the schools water and water. OK you can hold things in these vessels you can deliver drugs in the invisibles. If you really you know this is of course you know I talked about phases I mean this one has a mind boggling number of faces you know but there's more variables. There's the amount of water versus oil. There's amount of surfactant in general there's also temperature and you can get all sorts of you know I talked about these my cells and things like that but certainly you can get very rich kinds of other faces. And so but what we want to do course is to use this just to try to dissolve the essentially dissolve the sugar crystals not dissolve it all the way they usually sort of have some finite size in the cocoa solids into the cocoa butter. OK. And so the key for this is something called lecithin which is also surfactant molecule basically and what it does. Again this is. In this is showing a how you can stabilize the oil and water is the you put the oil in the water but you put the surf act in there right. And then the surfactant goes to the surface and it basically forms a monolayer of stuff on the surface and then that that drop is stable because to get it to be break to coalesce you have to sort of break off these molecules and they energetically don't like to do that. OK so that's how you stabilize the oil and water and that's how you're going to stabilise the sugar if you like in this cocoa butter. OK So for example here's the sugar crystal and it's sort of the reverse process where the head. Head of the surfactant goes near the sugar and the tails go into the cocoa butter right where the fat it which is basically oily and so you might get something like this you might get some of this also occurring around our cocoa particles but there's a debate about how that stabilized and whether it's just kinetically stabilise. OK So really that's what I wanted to tell you you know just hopefully conveyed a little bit. Now you can have the best part of the show but hopefully you conveyed a little bit about. Matter and phases and phase transitions and you can see that you know thinking about these problems as some relevance to. Understanding and controlling really chocolate. We can certainly ask question. So those are all solid. Yeah. No. So one phase is that's a good question. OK So the question was so I showed six pieces of chocolate. Yes So they certainly you have liquid at the high temperature and then depending on where you are the lowest energy. Depending on the temperature then below or becomes a solid OK there's a different free energy. If you look for those different phases. So different ones are stable at different temperatures. So it's like a saw it still is kind of like a solid solid transition the way that I've posed that you know actually to be perfectly honest when I've been reading about the chocolates. There's usually a mixture. It's not just one kind of it's like a fat molecule. And so that also makes it more calm so thank you thank you. Thank you thank you so much. Arjun I always learn so much in these kind of. SESSIONS And this is no difference. Fascinating and. I start out by saying that when I was first learning how to make desserts. You know as an apprentice working with pastry chefs. You would sort of naturally have curiosity and ask well why do we whisked this thing that way or why does this happen and in those days the chefs wouldn't answer you. They didn't know themselves although they would admit that they would just say well because just do it the way I told you that's why. So this is sort of my reaction to that and going deeply deeply into how. Matter behaves has become so fascinating and it's something that as we as food seems to take over every television show that we watch. It's it's great that there's this much interest on a Saturday morning beautiful day that you would come and hear us talk and it's it's very gratifying to me to see that. So just as a brief introduction I brought this picture. One of many to explain what I do. So this is a a cake that I made for reception. It's in the Blue Room of the White House. Beautiful drapes there that matched the walls the room was designed basically by George Washington. And James Hogan the Irish architect who who designed the White House the room was oval. So that's the origin of the oval it's not the oval office the Oval Office is a copy of this in the sense that Washington wanted. That's the main gathering room of the House wanted to be oval so there's no corners and people didn't feel pushed into a corner. This is after all for him his image of where people of different strains of diversity came together to talk and he was very conscious of this type of interaction. So one thing and we were talking about this last night to be in Washington D.C. has been such a exciting and and thrilling adventure for me and for one reason because you begin to see the absolute brilliance of the people who founded this country and wrote the Constitution and The Jeffersons Adams Washington's and Monroe and Madison and these they didn't come up with these ideas as a just kind of random discussion. They had read the histories. Of Rome and Gibbons Rome and they read the critique of the critique of givens Rome and they really came together and they were highly highly motivated to make this new country work and they used all their intellectual abilities to do so. And remember this is seven thousand nine hundred seventy when the Constitutional Convention was held and it still works today in a way. But the reason I say that it works and I'm convinced that it does is because one of the most interesting days of my life was to be in the White House on January twenty first two thousand and nine. So before that I was there for two years working with the previous administration and you have West Wing and east wing working very hard every day on their goals and I mean just as a chef we work with them because there's always some kind of entertaining that goes on when in the White House and so then on the twenty and the twenty first the offices are empty. This is the nerve center of of the executive branch of the government and there is no one there. It's fascinating to me and people start streaming in like where's where's my office Where's my computer and so what what I'm the reason I say that is that these founding fathers had this kind of confidence amenity and in the ability of human beings to solve problems together and know where to meet is that more evident in that than on January twenty first in a change of administrations. So today from the founding of our country to the squishy physics of chocolate it's a short leap and so understanding the world around us which is is what physics does I think and we're just taking a route to it that is that everyone can relate to delicious food and also sort of whimsical and fun presentations these are. Baseballs made out of chocolate as white chocolate with a red thread going around them and. So this is the type of thing that I make this is not mine but it was kind of a cute. Mickey Mouse version of what's called a boost in a well or chocolate log Christmas. So the log is layers of chocolate inside and then one of the techniques we use to decorate this kind of thing is we spray chocolate through a paint sprayer which is what this is that's that velvety surface you see on there. We actually to do that. Add more cocoa butter then use in a standard bar of chocolate. So bar of chocolate cocoa butter can have between twenty and thirty percent and it just depends on the quality of the chocolate cocoa butter is expensive because it is also used in the pharmaceutical and cosmetic industry. So usually the more cocoa butter. The more expensive your chocolate is but. That's all a ratio and no chocolate company will tell you what that ratio is that's their proprietary secret and so it actually just to get this is one of my favorite things to talk about to complain about really. So a few years ago you start to see percentages on chocolates which is as useful. What that means eighty five percent cow or cocoa all that's telling you is it's fifteen percent sugar. Which is useful. It's useful to know but it's become you see how big it is and it's bigger than lint. I mean they're like you know this is eighty five when really means nothing because although it's telling you that there's fifteen percent sugar. It doesn't tell you about those other elements that Arjun told us about namely the chocolate nibs they're sometimes called it sometimes called Chocolate liquor because no alcohol in it but they still call it that or cocoa paste so and the cocoa paste and the cocoa butter with the sugar is what makes the. The quality of the chocolate and primarily it's the quality of that cocoa paste because as you saw and maybe I think I have some some other versions of this we're going to come back to that. That it's the quality of what's in those beans that Arjun showed us those beans are how they're grown and what the the origin of their sort of plant genetics are the best quality one bean is called Creole You know it's a very difficult being to grow it's highly susceptible to pests and almost nobody grows it anymore. There's a few of them around one of them is a plantation in Hawaii that grows excellent chocolate cow being and chuff and burger used to have a product called porcelain and that was mostly Creole You know it's excellent. So the cheaper kind of chocolates called for stero forest arrow is what is grown throughout most of the world doesn't have the flavor profile of Creole you know but there is a third kind of culture an Atari zero and it's a hybrid of Creole you know enforced arrow and that chocolate is the type of chocolate that these premium bars are made from They're extremely fruity they have a very very wide flavor profile. There's you can taste raspberry even citrus all kinds of smoky coffee flavors and what you saw there with those little purple beans that are fermented is a really is just a microcosm of so much flavor. So by manipulating the two parts of the chocolate the physics of it. That gives it the structure and the flavor. That's what pastry chefs do. We're interested in both primarily really when it comes to you know the customer guest. We're interested in the flavor but you can do some wonderful things with it. This is kind of a little bit of a distorted image of a the winning sculpture chocolate sculpture. That's what's called the plate which takes place in Leone every two years and. People like me get all excited about this we call it the calling area lympics And so the teams form and they train for a year just like in the Olympics and. This happens to be the French teen which made this very sort of. The serious sort of sculpture. Made out of chocolate and all things out a bill basically it's a type of thing that we get all excited about anyway. This was the winner it's chocolate. Why is it so shiny well ask the people that made it and it's not because it's so perfectly tempered. Which as Arjun explain why that that happens because of those those crystals how they how they line up as you saw in his slide they line up all together and they reflect light more efficiently. This when they took salad oil and spread it all over and they won. OK so I'm going to go. I'm going to go ahead here and talk a little bit more about chocolate and we'll go back to some of those other things. So another sculpture this one is mine. Every year we make what's called a gingerbread house at the White House for Christmas and the kids come through and there's a very wonderful display of here in this case both on the left hand side there and we even inside each room we make we remake the furniture of the White House other chocolate in Mars' a pan and. So this is a way to use chocolate that's entertaining and. Which communicates sort of this incredible building and as we said these incredible people that that put it together and the philosophy behind it. Side view of that. And now on to the the beans. Arjun talk recently about it. I'd like to bring it up again because you see how this very like unhygenic sort of way the beans are fermented and then in most cases that is how it's done. And that that results in a lot of the quality of the chocolate comes from not only the quality of the bean that we talked about. But also how it's handled so in many cases chocolate is just a crop that's grown by a family and if you go to one of the chocolate producing producing countries. You'll drive along the road and you will see you have to stop because the family has the beans spread out on the asphalt drying. And so you have to stop the car and they come out and they sweep them off and then you drive through and then they put them back out. So actually that's the second phase so what you're seeing here is the fermentation that white covering is the fruit. It's a residual fruit the taste delicious by the way but it's really hard to to get off because or to really for a take advantage of it because it is it's a little it just covers the bean. So here's an example of the being a little bit more described intensively so they're gradation as advocation and Browning is what happens during that from an Taishan problem process not a problem unless you do it wrong. So the bean is as you saw a lump together with it's with its fruit white fruit sort of exterior there's a lot of sugar in that and that helps the from in Taishan too to take place as you see here the sugar turns into ethanol and as it begins to degrade the rest these other acidic acids and and other elements are created and not until then doesn't taste like chocolate. If you eat one of those beans. It's just a bitter very bitter and flavor of this bean. But when you but a time you get to the Browning where these where it has really fermented if you taste that bean especially if it's dried it just tastes like chocolate. And that's how people who judge and buy chocolate and process it make their decision because they'll taste those beans and sometimes they're not very bitter they're they're not sweet either there's very there's not much sugar left in it but that's where you taste those incredible floral notes the citrus and raspberry and all kinds of different aspects that a really high quality chocolate should have and so when you're tasting chocolate that's one of the things besides the appearance. You know if we look at chocolate it should be shining as we know for margin why because those crystals are formed. And it should snap as we as we've heard also because it's. Because there are they're very stable and they're very tightly packed together. So even if we heard that. Nothing but shiny and it's perfectly stable because it's temperature. So just like the bar that you bought and allowed to melt in your pocket and put back in your in your refrigerator. So I think I'll start out with with this process but since we're so deeply into it now. So now we have this amazing. Mixture of this combination of of chocolate liqueur or cocoa or cocoa paste and cocoa butter. And we throw it together and there's a whole process of bringing that those particles to smaller and smaller size the ideal size is twenty microns or less and that's where the chocolate manufacturer does let's see what we have there's a picture of a really good quality cow cut in half and you can see it's purple. So the really good quality could Kahlo you'll notice even in the chocolate that it has a kind of a purplish Hugh to it and. Can be a sign a good sign of good quality the old fashioned way the way the Mayans prepared chocolate was on this kind of table. So they would take a stone roller and roll it on this roll and on that stone still used today you go to a cow producing country where it's still Jews like Mexico or or Venezuela or anywhere that the Mayan culture and Aztec culture went and you will still see this being done in villages and it's fascinating. It's really delicious. They're taking their own cocoa. It's also quite gritty because they don't have the same kind of grinding system that we do the milling. But they'll add cinnamon and spices and sugar to this and they will sell it in a little markets as a kind of a little truffle a kind of it's kind of a grainy truffle but with wonderful chocolate flavor very intense and very floral. A more commercial way of doing it is with these grinders So not only are they grinding it down to twenty microns or less but they're also mixing and developing those flavors that happened during that acidification process of from an Taishan So those flavors are developed in this which is a ground grinding and also called conch in process so a really good if you're making chocolate in a hurry and you want to get on the marketing get your money you might cons for six hours to twelve hours a really good chocolate can be const for up to seventy two hours that fully developed those flavors it mixes them together and also makes the granules a little bit smaller. We saw this earlier this graph of how to melt the chocolate so that's what I'm going to show you the moment you heat it up never higher than one hundred fifteen degrees Fahrenheit for dark and for white chocolate. It should be even less and milk chocolate even less about one hundred ten maximum. And then we bring it down to depending on. Chocolate itself and it will often have a description of how to temper. So this one doesn't but that's OK now you know it anyway. So you'll sometimes see this graph on the side of the of chocolate bars which tell you exactly how it was manufactured and what you should be aiming for. But in general you can go to up to one fifteen back down to eighty two or eighty three Fahrenheit and then back up to up to eighty eight eighty eight is where is that C. sweet spot. That's where those beta five crystal start forming the fifth fifth dimension in there that we talked about that's the really the best spot so that's where the sugar cocoa powder and cocoa butter begin to form those that relationship that gives a nice nap and the best structure. So there was a question earlier about does it go through all those phases as you melted Yes it does so here. There is sort of this description they call it the formless stage type one the melting point and type two up to five which is the purple ideal one a little diagram of how it might look as it starts to come together as as Arjun explained the motion happens and if you do it right. It comes out like that. So this is a chocolate sphere that is one of our really fun desserts where we would make a very thin chocolate shell in a hemisphere globe and then we put a chocolate cake and ice cream and whipped cream and cherries inside it and when it's served the waiter comes and pours a hot chocolate sauce on it and the whole thing like kind of opens and reveals the inside. Great fun. The world's first kinetic dessert. I call it. This is if this is a an opera cake. It's a it's a classic French dessert. That is still. Used today still very popular. It's layers of culture cond and then usually a very thin layer of coffee butter cream or some pistachio some of the butter cream a layer of. And then this one too. As has that sprayed chocolate surface on it. Along with some attend your angel lay there. There is a very shiny piece of chocolate correctly tempered so that you see those those number five crystals. Well lined up which reflect light the best since there since they're all lining the same direction and that's why it's shining. OK so now on to the demo. So this has I melted this earlier. It came from this and let me get close to the camera there because I think you're able to see that the cocoa butter is already starting to since it wasn't. Here we go since it was is already starting to come to the top there's like little dots like you know like the salad oil that are don't explain with water. So it's already starting to come to the top it has not been tempered it's it's really disintegrated into that those two phases. I mean into those two elements of cocoa nibs and cocoa nibs and cocoa butter and the sugar. So let's take it back up. If you do if you do melt chocolate in a microwave you have to be really attentive. It's it can burn very easily if you go over that one fifteen. It burns and it forms these little granular grains of sand in there that you never get out now that you cannot retrieve putting in refrigerators OK or melting it in your pocket is probably slow melt which by the way who decided that chocolates had melted body temperature that strange. Like it's a plant. You know it has nothing to do with us. And yet. Maybe that's why. It was kept around for so long. So you had those Mayans and Aztecs usually the chocolate and there's beautiful drawings and Mayan art where you see the chocolate being used in ceremonies and you'll have it was usually prepared by the women on those grinding tables. But of course then in the ceremonies the religious ceremonies the priests were men and they just decided that it would be good to mix it with human blood. So you know they took that. And spices. Apparently it goes well with both but they were they were drinking it. They were they did not have this kind of chocolate in the New World. The first reference to chocolate in a new world is by Columbus himself he writes back that there was he came across the canoe where the Indians were had filled with these these beans that were so valuable that they treated it as if it were an eye. And this was these were cocoa beans cocoa beans and it was a currency at the time so it was valuable to them. But in any case a huge part of mine and that's the culture was based around chocolate and then came to Spain through people like Christopher Columbus and they they kept it basically secret for about one hundred years. So the Spanish court was drinking it. They were drinking it in the in the New World post Columbia world and nobody knew about it. It wasn't till the it was Inquisition. When Jews were driven out of Spain that it went into France and went in to be a Ritz and by you know in that area down there and that's where chocolate began to be known to Europe in general. And it had a huge a huge popularity of course the. The English and the French adapted. There were chocolate houses and tea houses and course coffee was coming around then too so there was coffee houses. Voltaire himself said that he never ate anything before three P.M. except chocolate. So it was that and he lived to be pretty old pretty smart guy. OK So this is a GREAT to monitor for chocolate it's unfortunate very fragile but it's one I highly recommend because each degree is very clearly marked on here you can get these things online but if you're interested in bringing your chocolate back to life that melted in your pocket. So bring it up to that temperature that we talked about where all of the crystals are melted so above about one twelve one fifteen and part of this process now is cooling it but it's also going to be what we do when we want the crystals to start to form and I am going to do what mention which is called seeding and I highly recommend it. So. We want to. To really melt as soon as it hits. The one chocolate. So we're going to make it very small pieces. Because as it cools course it doesn't melt right away after that. So we're as as was mentioned the slower the better. But we don't have that much time so we're going to speed this up by seeding it. And this what I'm doing is a very you know this is something every pastry school teaches you. The old fashioned tempering method. So if you're making bon bons or truffles. This is one of the steps that you would do. Ok you. Even though it's not cold it's colder than it was in there. The room is probably about sixty or seventy I would guess. So OK at that point we're going to bring in some of these the untampered by the way the best way to temper is not untempered to begin with. So in other words you would take. You would take just your chocolate and put it exactly eighty eight degrees and leave it for several hours and then it will never leave the tempering stage and you'll come back and be melted and you won't have to go through all of this. That's what a lot of pastry chefs do they just find an area above the oven. Keep a huge bowl of chocolate so it doesn't temperature does not change as quickly and then it's kind of always ready to use. So what we're doing is moving it around. We're allowing those crystals to fold over one another. We want them to take the benefit of that seed that we put in there. The chocolate that was already tempered and which has the crystals that number five crystal that we love so get it. In place. The reason we we chop it up is that you can see there's still a few little pieces left we're going to kind of squish those out the word of the day. OK As you can see because it's becoming more and more viscous it's not flowing as much as it was earlier. So those crystals are forming. At this point. It's going to keep going and usually it sets up a little bit too much so. Because we want to be sure we got it to the to the right stage. So we're going to put it back in the microwave for just a second to bring it up. It's one or two degrees. This is a very small amount of chocolate so if I was doing like. You know about four times. This would be a pound. I would give it about three seconds in the microwave at this stage. OK so. You are out of the way. I'll take a moment to thank Alberto and and the whole school here for having me. It's so much fun to be here and we had such a fantastic conversation yesterday learning about where food and physics intersects and so as I say I always learn a lot and thank you. Also to the graduate students and Perry who helped me put this whole show bang together. OK so getting very thick. And I'm going to just give it a second or two to heat it up. OK. So up to now it's what it was doing when it was in your pocket and melted and then you. You put it back in the freezer without doing all this so it became like Lumpy and coarse and granular and. And eventually the bloom would have come out Bloom is called is the cocoa butter that rises to the surface. Since it's not I'm also fied. But here you can see that since we went through all this. It's already starting to A to set here very very quickly. So that's. Sign too that you are. That's a sign that you have to get rid of this extra here I want to show you that you've tempered it correctly because correctly tempered chocolate will set up almost immediately. So who what am I looking for here. That. Well you can see where it's almost what I would call it dry. You see how it has dried along here as opposed to shiny. So it's a different kind of shiny when it's wet it's real shiny or if you put salad oil in a competition on your street. But the kind of shine that we want is is this one where it's shiny but it's and it's set almost immediately. And so what we'll do know is what makes them so thicker versions of this. And. It's a little warm in here so it's going to take. I think longer than it normally would. But we'll just let it sit here and we'll come back to it. This by the way is a. Is kind of a very classic. Decoration for a cake you just take a spatula. And you make like dozens of these sort of little petals and then when they set you pop them off the plastic and put them on top of your cake it's a it's a cake that was developed by public crews called the president's cake and it's really kind of cool. You always wonder like how to finish a cake but if you put butter cream are going to shine and it doesn't have much flair. But if you do something like this then you can put it in and have a sort of rose petal look so while that's setting and I'd like to find maybe a place that's a little cooler I think I'll set it here. I think we'll get there. More air currents here. So. So I'm kind of starting backwards because what I wanted to do was was to make a play to dessert for you that we have over here and do it one by one and referring to the science that we learned earlier about chocolate. So the one thing I want to start out with is what I call the forty five second sponge cake. So it's a very interesting and unique cake was developed by Fran Adria and it's something that if you have guests coming over. I'm at the front door. You could have this dessert by the time you by the time they get to into the house. So it's a. And that reminds me I think these recipes be nice if we have them of vailable two on the website or something. So this recipe is is a mixture of four egg whites three yolks. Fifty grams of sugar cocoa powder and a little bit of tahini paste. So the original was with black sesame paste but I like this to paste just something that gives a little sesame flavor a little more dimension to it so and so what you do is you mix that together and you pass it through a sieve because you want to bring it put it into this what we call an easy form or or whip cream from or there's two kinds of gas that you can put in here one is the. Is this one the soda Charger's which is for a club soda don't use that because it has that kind of salty flavor. And then. But what you can do is these whipped cream Chargers which is what's in here. So. That makes sure that I just described you pass through the sieves so it's nice and. So it's nice and uniform no lumps you charge it with I think I'll put one more charge in because it's been sitting here for a while so. Let's and also so you can. See what we do. So in here is rock a better. FACE. These are paper cups a little hole cut in the bottom because so the steam can escape and brushed with a little butter off I'll try not to spray the first row over there hopes. No promises. OK So there you have instant cake batter. So what you normally would would take you twenty minutes or so on the mixer. Normally would take twenty minutes or so on the mixer you know waiting for that foam to happen which happens very easily especially if there's if it's egg whites and you put a little cream of tartar in there than that acid helps the albumin to break down and you get a Marang if you're using whole eggs. Then the less than of the yolks also makes that happen more quickly. Because you're you know it's creates that surfactant that we talked about earlier which enables that phone to stay and be created. But this is kind of fun too. So don't fill it up very much because there's so much air in there now that you're going through it's going to overflow. If you put more than a third of a of that cup in there. So let it go for about this this microwave is really strong. I do it in mine. I do forty seconds on high but this one only took about. Only took about thirty. So yeah it's starting so it cooks it. In a very uniform way I suppose if you wanted to make a whole layer cake. You'd have to find something that wasn't metallic and put that in there and hit the on button. Going to another then another second is anybody counting good. Whoops I understand it's not good to let those things run you're adding to the microwave of the universe or something. So. So you're you're thirty five seconds sponge cake. OK. T.. It's I think it just needs a touch more of this feels a little bit. OK. OK. So as we make our plate then yeah this is this is still very soft what I would do if I were you know really making this is I would let it cool down a little bit. But here this is interesting you know we're talking about phones and how they form. So you have some very big holes there that are. Formed by the egg and the protein in. And carbohydrates in the flour and they immediately seized around that. So OK this goes over here. They immediately seize around. Those bubbles and form the bubble there. So the next thing I'd like to do is not actually chocolate but I always like to have some fruit flavors with chocolate something to to give a little bit of contrast and so what I made here is it's also a kind of a fall. It's made with modified so I protein. It's all it is is strawberry puree So first strawberries push through a put in the blender and then push through and push through a sieve. What am I missing here. One element of. Thank you. Thank you. Show. OK So we are with it just goes right on there obviously not technically. OK so modified soy protein and strawberry puree right in here. So it's if you have a blender at home. You could do with the blender. These these devices we call immersion blunders have is great because it has all the different tach moments like you can do a whisk which we're going to do in a minute or you can do this which is kind of like a food processor. Or you can do the actual immersion blender with this blade which is useful also especially with this type of cooking if you want to call it modern Modernist Cuisine a lot of these hydro coal oil. Do not blend well with liquid so you have to shear them into the liquid. And that blender is what we use. Reverse. OK so. This I'm going to leave over here. So it was just a strawberry puree and now it's a very bubbly sort of liquid the next step and this recipe is you know you place it on parchment or something that we like to use in pastry is called So Pat It's a silicone sheet. You can get them at Williams Sonoma or. I get five cents for each one. First I just know it's. So you spread that out on a sheet with a spatula and you come up with. What I call Strawberry bread. So it dries out but because it has that protein in it. That's why protein the bubble stay. It doesn't just collapse and then you would wind up with like a fruit leather which is fine to kind of interesting but this makes these little sort of your shape decorations and it stays snappy so. Still crunchy. And gives a nice texture because so far we have an elastic texture over here elastic to sort of. We're going to get to this other going to last year which is very interesting. So it's nice to have a crunchy sort of touch to it. So now they're running you see former I'll show you another way to make a really interesting most chocolate most of that is a fairly classic recipe. It is half milk half clean a little bit of sugar and and convert your what we call culture or just plain chocolate. So there were making a chocolate mousse But why stop there. Everybody knows what chocolate mousse is we're going to freeze the outside of the chocolate mousse and leave the inside. Liquid which is gives a very interesting kind of crack and crunch when you. When you bite into it. So that's one of the things that a chefs were looking for is a unique experience a texture that people have not seen before. And which is just intriguing. Sometimes things taste better too. Depending on their their texture. So if it's if it's called on the outside and then all of a sudden you bite into it and you have this awesome like room temperature chocolate. The surprise sort of wakes up your palate and you taste it more thoroughly. OK so. Just you know you're liquid nitrogen the same one you have a home. So we have we found these cool little these hemispheres here you have to put that in first. So it gets real cold and otherwise the chocolate of course is going to stick to it but since it's super frozen here. Once we want to put the chocolate in that crystallization is going to happen. Hardening. Crystallization is going to happen and it will not stick. OK So let's take this again I'll try and do this without spraying the front row. I don't know how you can see it. OK. Oops. Well this didn't come out quite as a sphere. It's more like one of those something they see. In their telescopes whereas Pablo you know so this is like a sort of asteroid or Anyway just takes a few seconds and all we've got are I forgot my strawberry bread. OK a little strawberry bread over here. And now. So the idea is when you're when you're serving something like this in a restaurant. These are the type of things which you put on at the very last minute. It's what makes it a plated dessert in a restaurant the most exciting way to have dessert in my mind. So it will go right out and the guest will bite into it while it's still crunchy on the outside. So it'll stay maybe forty five seconds like that it's so extremely cold so liquid nitrogen boils at something like minus one ninety nine cent a grade seventy seven. Kelvin very cold which is kind of interesting because one and one of these demos that I was doing. Summer is mentioning how how unique water rears and how what an incredible substance it is it takes so much energy to boil water to separate those bonds that Arjun told us about the hydrogen next to the oxygen. So you have to heat that to two hundred twelve Fahrenheit. In order for it to boil. That's so much energy. Whereas liquid nitrogen it's going to boil at minus three. Twenty one. So when you think of what I mean what is the temperature in the universe of empty space water is an extremely stable substance. So let me try another one here. Off. OK And what I want to try and where so how about on about understeer want to help I need an assistant can you come help me up here. Come on and you're good to each Ochlik. OK All right. Volunteer Here she comes. All right let's have a man. What's your name three hundred on young very nice to meet you I'm Bill. Come on over here. OK so what we're going to do is we're going to make this little chocolate mousse and what I'd like you to do. So this is very cold. Don't touch this all I'm going to have you do is you're going to shake this put your finger on there maybe a better stick for you are the worst the front row is very nervous when we are doing this they know they're going to get. OK so what I want you to do now I'm going to hold this with my tongs and you just pull this lever but very very slowly. Otherwise I'm going to get it all over my face. OK you're up for that. All right so you hold it like this and I'm going to hold this and then this is the liver just pushes slowly as you can. That's right. Perfect. Wow you are great chef gratis. OK let's put it in here. Awesome. Thank you very much. Yes Great only Yeah well wait a second you get to taste it. Since you help me. OK nice little crunch on. It's a little bit. OK to me which I think you are seeking heard yes that means. Thank you. OK. Pardon my mouthful. OK the next element. I like to talk about. One of the reasons that chefs want to learn about science want to learn how things grow where they grow how they distributed everything you can. And even on their molecular level is we want great flavor. But we'd like to be healthier if we can. So I've been very proud to be part of Mrs Obama's Let's Move program. Let's Move initiative where we talk to kids about healthy eating about about what we eat where it comes from and how if we don't need good things our lifespan is shortened. So we can look at desserts which is something that is probably no one thinks of dessert and healthy in the same sense except me but I don't know that there's anything. There's probably no such thing as a healthy deserve. But there is a healthy lifestyle that can include dessert in moderation. So that's my message and one of the things that I like to do is I like to play around with. Recipes. Using science to eliminate some of the fat sugar and cream and cholesterol that we are so familiar with in our desserts. And a really great recipe. And this is this is by the way has been around for a long time and it was developed by every one of the sort of founding fathers of molecular gastronomy and he's been working on this stuff since with Nicholas Kirti since about one thousand nine hundred eighty eight. So we're like into almost fifty years of molecular gastronomy which is crazy. So this is a chocolate cannot. Without milk or cream. So Arjun explained to us that chocolate itself is an emotion. It's this fat cocoa butter and then the cocoa nibs and sugar. So we can consider that a kind of a water and of course the fat is hydrophobic it doesn't want to mix with water but the sugar and the cocoa nibs are complex leet hydrophilic So chocolate so this is an emulsion but we. And that gives us a pleasant flavor when it starts to come together so oftentimes we're making the recipe such as we want to maintain that emotion even though we're adding other ingredients. So the standard is just heavy cream and chocolate covered your chalked up you pour the heavy cream over the chocolate and you whisk it right from the beginning and knows it's the caffeine which is in milk and cream dairy products which becomes a surf active. And that emulsion then takes place and you have a very smooth very anxious wonderful thing but can we do it without cream. When I was first you know asking no chefs why why do we do it that way and they said you know just do it they would say Well and by the way. Never let water get near your chocolate. OK. Why's that. Just don't. So the water because you have that emulsion of fat and cocoa nubes is. It's fairly fragile and if you add water to it and the molecules don't like it and they will start to start to that what you want to call it that emotion breaks down don't reward your chocolate. Well it turns out depends on how you put the water and how much you put. So I have a recipe which I can give you if you have a pen. It's two hundred grams of water and I think we have time to do this. OK So two hundred grams of water one hundred fifty grams of chocolate covered her. So that's you know just a bar chocolate but use a good chocolate like this one. You can use baking chocolate or or and you could use milk chocolate white chocolate probably not work that well but and just a little quarter teaspoon of gelatin powder gelatin that has been bloomed so you bloom means it's been it's sat in some water for a few minutes. So here's the water. And I think I've I've been eating the chocolate all morning. So I probably don't have enough left to let's see. Maybe we can maybe we can still perform this bear with me. So what we're going to do while I'm measuring it I'll explain to you you boil the water. Add the gelatin to the water poured over the broken up chocolate or in this case it's going to be the some I melted chocolate away. Hole in the bottom but try this. I'd like to show you this in real time because it's and I have I have one that's already prepared but. This is more fun to watch. At least you'll see how to do it. I really don't have any gelatin not too but OK I'm going to make a half recipe. So we boil our water. Have our chocolate which can be tempered around temper it doesn't matter because we're going to reintroduce the emulsion with our whisk there. While that's happening I'm going to show you to the end result sort of Julia Child style known for the more so. So this is the good notch that results from this which is amazing because this is water and chocolate. We're told that water in chocolate doesn't become anything nice but look how smooth and anxious this is. It's a it's a beautiful. And it's water and chocolate. So we're going to get to that in a moment I'm going to show you how to make it. All right. See how our water is doing. I love this microwave gun super charge that you physics guys. We don't want to know. Don't tell us so. Ok water the chocolate and then. Our old friend again. What would a pastry demo be without liquid nitrogen. OK We have hot water and we have to talk about it. Now the air bubbles. Are going to form. Because we're risking it with this. We're going to need the bubbles are going to be captured by the Christianization of the chocolate. So instead of crystallizing like it did here in just a two dimensional shape. It's going to crystallize around the bubble. That's why you wind up with this instead of that. I need another volunteer work with my assistance. Can you help me again. OK Come on come on come on. There we go. Thank you. All right. Yeah a little hot Little Rock. Come on. I mean here you go. So you have to push this button down. OK let's see what. OK There you go. You got it. Keep holding it there. I'm going to put something over it so it doesn't keep going to take a while though right. You threw them in the pool. And. Your mom is going to be really mad if I send you back over there. With. OK That's a look at it later the now let's see that. OK. Just hold on hold that like that are not too close. Just don't put your head in there. I don't want to because there you go. Right here and then push. Perfect. Break. Thank you keep going keep going. OK well what are you. So just a little technique about how the way we think in pastry shops restaurants is we just love canals can also these football shape. Sort of things. And so. And I wanted to do this so I can give you. So I can show you how smooth this water going is. Having fun. For me too. OK. So you can see how this. With a one spoon. And here you can just get this really awesome very smooth can now. OK let's see you. OK. Once you taste it put you put your finger in there and taste. If you like a good OK endorsement but I understand you sir thank you. You can go. Thanks buddy. Appreciate your help. All right good job. Can you have one of course you can. It's been right there you go. Yeah what's a little dip the finger that's not going to talk on work. He needs an agent. OK where were we. OK. How how that works. I mean we're taking a little longer but it's already starting to set up and eventually it's going to look like this. That's our Water for Chocolate. So what do we know we're just missing our flowers. You know that's. I had nothing to do with those. But we this is from Chef Gardens one of the really fantastic organic growers in the States here on Ohio growing absolutely delicious registerable Zen etc and then we just need a little bit of of chocolate sauce which we've momentarily. I know I know we need we need our decoration too. So they have our canal is really cool. It's set. So the chocolate has set and it's one of the telltale signs of a well tempered chocolate is that there's no white markings on it because the cocoa butter would have risen to the surface by now so we have a we've we've saved your chocolate bar from. From destruction. And so they come off as one piece. These I love this acrylic this acrylic is perfect for chocolate by the way this is just a little too stiff for me because I'm not strong enough to get it off there. Can I break it. OK. Yeah a little thinner would be better but That's right. I got to show you the shiny part. So of course it's the the under part the part that's against the acrylic which is is the shiny assist. Take my word for. OK. So. There you go OK. So squishy physics. THANK YOU THANK YOU THANK YOU THANK YOU.