1.1: The Great British Bake Off (Soggy Bottom Science)

[Music] Hello and welcome to Smalls Green Science, the brand new podcast where we take a look at some of the science behind our favorite TV shows. I'm Karen Collins, I'm a science teacher, an educational consultant and a science communicator. And I'm a member of a Christian, a communications specialist, a podcaster and a science communicator. Now this week's episode is called "A Suggie Bottom Science" because we are going to be looking at the Great British Bake-Off. We're going to be talking about the science behind baking, getting food right and why we enjoy it so damn much. Yes, absolutely. And each week we're going to try and sneak in some catchphrases or some terms relating to these TV shows for you to try and spot. Now because we're starting with Bake-Off, we thought it was only right to start off with some baking puns and some Bake-Off in new endos. Absolutely. So see how many we can fold into the episode and we'll give you a full list at the end. There's the example of the first one there. Thanks for you looking out for it. Because after all it is compulsory and we're going to throw in definitely some Bake-Off in new endos because you can't do Bake-Off without the in-new endos. Absolutely. And also because it is our first episode and we're going to be talking to an expert about why we enjoy chocolate. There's a small chance. There's a big chance. We've definitely bought ourselves some bars of chocolate to enjoy later but it's all in the name of science. We've got an experiment lined up. Yeah, because after all, who needs an excuse to buy chocolate? Okay, well let's get started with the episode. Karen, I've got a bit of a treat for you actually to start this one. What do you reckon this is? That looks like a delicious loaf of bread. That is actually, I'll be honest with you, this smells fantastic and I'm not bragging because I did make this. Yeah, so we've started this episode. We're going to talk about bread and sourdough. I've never been a baker particularly but I have to admit in the last couple of months I've really gotten into sourdough. And this is actually the second loaf of your bread that I'm actually going to taste. And the one I had yesterday was delicious. Are you lucky? Yeah, I have to admit, this one's got that good sourdough tang to it. I'm starting to get better. My first loaf was absolutely atrocious but I'm slowly working. There's such an art and a lot of science behind what goes into making sourdough. Sourdough loaf is really. Absolutely. And what's exciting about this sourdough is that it actually has come from a starter which was a gift and is called mother. It was so that might be a hint to our first guest on the podcast. So those of you that watched season was 2017. That's right. Great British Bake Off. You might remember a scientist Jan Sue. We actually went to go and speak to her for this episode and she very kindly sent me a sample of her now famous sourdough starter. So the way that sourdough works is you keep this culture of yeast alive and you feed it regularly with a bit of water and a bit of flour and it keeps bubbling away. And then when you're ready to make a loaf, you use this starter. You add to it a lot more flour and a lot more water. And that's got enough yeast in it. It's got enough activity in it that it will create the loaf as opposed to adding like a packet mix of yeast or some dry yeast. Yeah. And the tangy tanginess actually comes from the bacteria which are growing in there. So you've got something like lactobacillus which is living there and producing a slightly acidic taste. And that's what gives the tang to this type of bread. It does mean that the starter absolutely stinks. But it stinks in a good way because there's so many things going on in there. Like you said, you've got so much other bacteria that you wouldn't get in a dry packet mix that this is what really kind of makes the bread unique. So I've been working on that and it takes a lot of commitment. Like sourdough takes about a day or two sometimes even to mature properly to get the dough even in a place where you can put it in the oven. And fun fact is that today's recording session actually started a little bit later because we had to wait until we were waiting for the bread to cook because it's so temperamental. Yeah, you do get to know your dough. Sounds a little bit sad. But I couldn't serve your soggy loaf. No, absolutely. It had to. So the knock that you heard right at the beginning there listeners. That's how you know if your bread is in that oven and you take it out and you can't quite tell whether it's ready or not, you turn it over and you tap on the back. And if it starts to make a tapping sound as if it's a little bit hollow or like you're knocking on a door, that's how you know it's probably cooked through. Yeah, and that's what we were waiting for this morning. We were waiting for the night. And it's well worth it. But that actually wasn't the reason that we went to go and see Jan, was it? No, absolutely not. No, because what we were interested in is pies. And it's more specifically the pie equation because when Jan was on the 2017 bakeoff, she actually mentioned the perfect pie equation. And the perfect pie equation was written by Dr. Eugenia Cheng. And she's produced a whole paper on this looking at, you know, how do you make the perfect mints pie? Oh, I'm looking back. And you cook mints pies as well. You may some overcrisis, didn't you? So I'm going to ask you a few questions as we go through her paper because I thought it'd be quite interesting to look at, you know, to look at pies and how do you make the perfect pie. So her paper is actually talking about something called the frustrum and she actually came up with an equation for the perfect pie. And I think Emma, you should have the same equation. Right. So I've got it in front of me. I'm going to try and read it out. So it starts with it's pie over a square root of three. Two brackets and inside the inner brackets, a capital R plus a little R over two first bracket cubed. Take, okay, minus R cubed end of second bracket. Actually, I think that came out quite well. That was quite impressive. But obviously this is, again, not brilliant for the audio medium. So head on over to our Instagram account and we will have a beautifully written version of that equation for you to take a look at that. Just in case you're interested. Yeah. So the idea behind this is to do all to do with cones and something, as I said, called the frustrum. So what I want you to do, listener, is to imagine a lovely Cornetto, maybe a nice mint Cornetto. That's what I can do. Yeah, you got that in your head. Yeah, lovely Cornetto. So unwrap your Cornetto and take a look at it and you can see there's the cone and then at the top still carrying on the cone shape. You've got a little bit of ice cream at the top. Take a knife, slice off that ice cream off the top. Or eat it. Yeah, or eat it. No, you've got to slice it off the top. If you want the shape, so you're going to slice it off the top and we're left with the cone at the bottom. And it's actually the piece that we've sliced off at the top. That is a frustrum. That shape is a frustrum. Now in mathematics, those of you are into mathematics, no. If you want to find out the volume of a frustrum, what you have to do is take into account the two cones that are involved in that shape, creating that shape of the frustrum. So that's the initial Cornetto shape before you take the ice cream off and then the cone that's left afterwards. So those two cone shapes. And actually, if you're baking a mint's pie, let's take your Christmas mint's pies that you made. Ugly pies, I call them. Not pretty, but tasted, didn't you? Yes, they tasted great. I hope they weren't lookers. They're not winning any competitions. Again, head all over to Instagram account. Oh, yeah. I'll put up a picture of my hideous mint's pies. But if you think about your, you're going to make some mint's pies. You don't take a cone of pastry and then cut off the bottom of the cone. Absolutely not. And use that top part to make the outside of the pastry case. Totally ridiculous. So explain to us how you would create, you know, what shapes you would use in terms of the pastry when you make a mint's pie. So you roll out your short cross pastry, you get it to a nice even thickness. And then I use two separate circular shapes, whether that's like a glass or a cup or an actual cutter. And you have a larger circle and that fits in the base of the kind of muffin case tin. And then once you've loaded in the mint's, you put the smaller circle of pastry on top to close it up. Exactly. And this is what this paper is all about that as a baker, you want to find the volume of the frustrum from the radius of these two separate circles, not looking at the cone at the start. So what she's done is done a whole load of amazing mathematics through the paper, some of which is a little bit over my head. However, she actually comes up with a final equation where you can work out the volume of a mint's pie using these circles. And the reason why this is important is obviously in order to get a perfect mint's pie, you need to think about the volume in the center and actually how much mint's meat are you placing inside the pie to get that nice taste. So there's not too much pastry and there's not too much of the content in the center and you end up with the perfect mint's pie. I can first have read the entire thing. I've left that up to science teacher Karen to dissect that one for us. But but Yanny had read it and we went to go and speak to her about pies and not just not just sweet pies. She actually even made us some safe, very pies to meet with her. So she's already favorite podcast guest straight away. Absolutely. And they were delicious. I have to say. So we're going to play a little clip from that now. It's in the Francis Creek Institute where Yanny works. It is in the cafeteria, which is obviously very relevant and very topical for a podcast on food. I mean, there is a little bit of background noise. So just bear with us as a few clankings and people wondering around back there. If you have with the pies, I'm all alone. They look absolutely delicious. Thank you. Thank you. Yeah, you've surpassed our expectations already. So talk us through them. What have you presented us with? Okay. So these are. chicken cats who curry pies. Oh, so. So, saying. Hello. So, one of the things I bake, some of the things I bake are based on things that I can't get. So, if I want to pie, I can buy a pie. That's what most people say. I can buy a pie. That's true. But can you get a chicken curry pie, and I do like my curries, and even better if it's in a pie, because it's handheld and you take it anywhere. So, how do you prevent a pie from getting a soggy bottom? You could probably, if it's a deep, deep, well pie, you could probably, uh, blind bake first, and then add it on top. You can also make sure that the filling is well-cso, mince pie is cooked already, and mince mince is cooked already. But if you were to say, "Do it on meat pie," make sure the filling is already cooked. So, you don't need a long length of time on the low heat, because then you're just getting the. And also that the filling isn't too wet. Because one of the big criticisms this series is the fact that their pie fillings were too dry, so they'd overcompensate it, to remove too much moisture. The fear of the soggy bottom has covered, has shadowed everything in their midst, but you're right. But you can also add moisture off the fat, so like pork pies, pork pie makers, make a hole at the top, and then as the pie's cooling, they pour like a gelatin mixture on top to fill all the areas, so it's both moist, and actually as it cools down, it solidifies, so it doesn't soggy into the pie. But also, I, personally, if I'm making a hand-raised pie, I brush the outside of egg white to stop it from leaking, because that can leakage, can also create a dry pie and a soggy bottom. But yeah, just experiment and find your own pie navana. So, dry pies, soggy bottoms, leakage, and pie navana. Pie navana, I would get that on a t-shirt. That's brilliant. You managed to sneak in soggy bottoms into that interview. Yes. I don't have proud of yourself managing to get in a few bake-off in New Endos. Yeah, definitely one of our bingo words. And I have to admit, if we were talking about pie navana, we were two very happy pie eaters on the train home after this, weren't we? Oh, yes, absolutely. Yeah. So, one of the, one of the kind of main reasons we also wanted to talk to her on this episode is of course not only is she a brilliant baker, star of bake-off. She's also a biomedical scientist. She combines the two kind of concepts of this episode, food and science. So, we were really interested in how much science she actually uses in her baking. Does she consciously use, you know, scientific theories and scientific understanding in her baking? A little bit like that pie equation we talked about earlier. Yeah, do you find that you approach baking then from quite a scientific back, like, do you look at it from quite a scientific perspective? Because when I cook, despite also having a science background sort of, I frustrate people that I'm cooking with. I don't like following recipes, and I like to do it from how I feel and how things look and feel when they get together. But do you approach things from like a much more methodical if I know how these ingredients work together? I know the process is kind of one of you. Actually, I'm probably more like you. I do follow it to an extent, but also I do like to experiment. It's like you said, I've had prior to two years ago. I haven't experimented with, so it's quite new though. It's aquafaba. Okay. Theoretically, it should work just like an egg white, because egg whites is protein. So this is the liquid from the. The liquid from chickpeas. It's so instance, I can replace egg white with aquafaba, but I can't replace the sugar, because I know that the sugar helps it crystallize. If you use that low calorie sugar or the no sugar stuff, it won't crystallize the same way. So as long as you understand why things work and how things work, you usually overcome certain problems with baking. So if you're making something with sugar, but you want it low sugar, and it has nothing to do with the texture, then you can usually do it. So like, for instance, if you're making a sweet pie crust, the sugar has no bearing on the texture. It's more like the butter and the fat and the flour. So you've got an element of emotion and an element of science in your baking. It has to be. And a lot of it is from cooking, so I'm also on cook. It's not just about baking. It's gut and feeling and. You know what things combine and taste and how they should look and how it should work. So we drifted back to pies almost a little bit there, but I cannot believe Karen that you got through that interview. We started talking about egg whites, and you didn't say your favourite words. Stiff peaks. No, and even better, voluminous stiff peaks. How did you let that slip? I know that was a bit of a disaster, and we only realised on the train on the way back, but luckily, the delicious pies made up for the fact that I'd missed it. Well, I think you should make up for it now. Stiff peaks, egg whites, talk me through. Okay, so egg whites are mostly made of water and protein, and it's the protein that's really key to getting the stiffest of your stiff peaks. So this is a technique often used when you whip up egg whites, particularly for things like morangs. Absolutely, yeah. And basically, what happens as you beat the egg whites, the protein inside them is denaturing. So it's structures changing, and you're also incorporating air bubbles into it. And that's the stage where it just looks bubbly. But if you want it to form these stiff peaks, what needs to happen is the protein needs to cluster around the outside of these air bubbles, and it forms a mesh around the outside of the air bubble. And once you've got that mesh, then you've got the stiff peak. So that gives it the structure. Absolutely. So for this to occur, to be able to create this actual structure, we need to eliminate the yolk, don't we? And this is because the yolk is full of fat. That's right, yeah. So the fat, when mixed into this, will pop the air bubbles, which are obviously essential to making this peak. And it does this by pushing the egg proteins actually away from the surface of the air bubbles, and that's what pops them. So if you're trying to whip up an egg and you've left the yolk in, you're not going to get a stiff peak. So you're going to get a nice, frothy mixture perfect for scrambled eggs, but not for morangs. No, and that can even be if you've got a greasy bowl. So you're going to make sure that there's literally no fat present at all to get the perfect, voluminous, stiff peak. Oh well done. You look so proud of yourself. So let's move on to the reasons behind why you put four bars of chocolate in front of me and talk about some of our favourite foods. Yeah, and when we think about food, we're often thinking about the smell of the food, the taste of the food, the texture. But we don't often think about the sound that food makes. Not at all. Never crosses my mind. But it turns out that actually food acoustics are really pivotal to our enjoyment of food. So to find out a little bit more about this, we went to go and speak to Megan Poevie, who is a professor of food physics at the University of Leeds School of Food Science and Nutrition. So my background actually is food chemistry. I did food chemistry degree before I became a science teacher. And I'm very interested in the fact that you are a food physicist. And we did quite a bit of food physics in my degree, but mostly about fluid dynamics and that kind of thing. And what interests me is the fact that you are actually looking at acoustics and the importance of that with food. So would you be able to tell us a little bit about your research? Yeah, we're interested in the way in which the sound food makes, influences our feelings and thoughts about it. And it became clear to me that if a food did not make a sound, then it couldn't possibly be crispy or crunchy. That crispy crunchiness is directly related to the sounds it's making. So these sounds were associated with cracking in the food. So on one extreme you'll have the snap of chocolate, which is a single crack. Or lots and lots of cracks in say a rice crispy. And each crack has a sound pulse associated with it. And our brains are actually counting the rate those pulses arrive. And that is how we decide whether something is more or less crispy. The higher the rate of the pulses, the more crispy we think something is. And then there's a tone associated with it. So if there's no low notes, we think of it as crispy. If there are low notes as well, then we think of it as crunchy. So she's picked out two things there. The crunch and the crackle as the two things that we want from food. Yeah, because of that kind of crispiness and the crunchiness. And the reason behind that is because evolutionarily, if we were for example eating fruits or back in the hunter gatherer days, you bite into an apple. And when that apple is fresh and when it's right to be eaten, it's the best for you to eat. It's really crunchy and you do get that very distinctive crunching sound as crunchy into an apple. And then of course marketing, it's used quite cleverly and marketing this kind of sound and acoustics within the packaging of food. It's so it's so sneaky how they trick us guys. So if you, for example, were looking at biscuit packets and you were looking at some high end biscuits, they often have really nice kind of quite crackly and quite crunchy packaging. And that's because you're already interacting with these sounds and it's already getting this idea in your mind that this is going to be fresh and it's going to be good quality. So these brands know that acoustics are really important how you determine your enjoyment of and the value you place in their food. Yeah and if you take something like crisps, for example, the crackliness of the packaging is mirroring the experience you're going to have with the crisps so you're anticipating the taste of the crisps by opening the crisps packet and hearing a similar sound. Sneaky, isn't it? I can feel my mouth watering already. So crisps aside, Mae'r angen yn agor ei fydd yn gweithio gynhyrchiocholod yn ymwyr. Mae'r gweithio gynhyrchiocholod yn gweithio gynhyrchiocholod yn gweithio gynhyrchiocholod yn gweithio gynhyrchiocholod. Mae'r gweithio gynhyrcholod yn gweithio gynhyrcholod yn gweithio gynhyrcholod yn gweithio gynhyrcholod. Mae'r gweithio gynhyrcholod yn gweithio gynhyrcholod yn gweithio gynhyrcholod. Mae'r gweithio gynhyrcholod yn gweithio gynhyrcholod. Mae'r gweithio gynhyrcholod. Mae'r gynhyrcholod. Mae'r gynhyrcholod. Mae'r gynhyrcholod. Mae'r gynhyrcholod. Mae'r gynhyrcholod. Mae'r gynhyrcholod. is a problem for me. Well they say that's quite a common problem, you know. So we decided to do a little bit of research to bring in some science and find out how to bake the perfect cake. Yeah and it turns out there's quite a lot of reasons why my cakes don't rise. So potentially I'm doing all of these mistakes, but we'll see. What's your cake of choice? If you had to bake a cake. If I forced you to bake a cake. I have to say I am a big fan of date and walnut. Oh, nice. Yeah, but I haven't really had had to go at baking one, which is a little bit bizarre. But date and walnut, lovely. Well, you better bring one to the next episode, I think. Do you think so? Yeah, absolutely. So, you know, I've got to ask. Mm-hmm. What's your creaming technique? [LAUGHTER] Yeah, because obviously that is the first stage of making your basic Victoria sponge is creaming. Yeah, you get it. All the recipes sit, cream together, the butter and the sugar. Yeah, and actually it turns out scientifically. If you don't get that right, then you're not going to get enough air in the cake, and that's potentially why it doesn't rise properly. Oh, OK. So when you incorporate these gas bubbles into the sugar and the butter by vigorous creaming. Oh, all right. What happens is these air bubbles are kind of on the surface of the sugar crystals. And this is one of the reasons why you use castor sugar instead of granulated sugar. Because castor sugar, the crystals are much smaller. So that means, you know, overall there's a bigger surface area for these bubbles to form that. So you end up with more bubbles. And then as you're creaming, the bubbles are encased in a layer of fat. And that's what creates that foam. And you'll see the colour change from a darker yellow into a very, very pale yellow. But if you don't cream it enough, then not enough air is incorporated. And therefore you get a poor rise on the cake. This is quite a task and work as well, though, isn't it? So actually, funnily enough, a really early cookbook, which was published in 1857, suggested that you got one, one got one's man servant to do the creaming. You know, all creaming should be done by man servant. Oh, Aaron. That's it. I'm not coming round to bake with you ever. So, so the next reason why I'm not getting a rise potentially in my cakes is about the beating egg. So if you've got to beat the egg enough to be able to get air into into that mixture as well. And when you add the egg to this creamed mixture, and what it does is it stops the fat covered air bubbles from collapsing. And that helps to form an extra layer around each bubble. And that helps also provide most of the liquid to the cake as well. So the eggs are actually quite crucial. Ah, well, you don't want to dry cake, do you? No. Now, once you've made your mixture, there are three more stages to baking your cake. You might think there's just one, shove it in the oven. But no. So these three stages are rising, setting and browning. And you don't really have to get involved in these. These all happen in the oven. But you've got to make sure the environment is ready for the cake to do these things. So the first one, the rising is all down to the air bubbles. So you've done your creaming and your beating, and there's loads of air bubbles in your mixture. And as soon as you put them in the heated environment of the oven, they expand. You know, their gas, gas expands when it heats up. And the water in the, or any of the liquid kind of in the cake also turns to steam which adds even more rise to the cake mixture. Yeah, so that's causing the, you know, these pockets within the cake to become larger and creating the rise, yeah. That's what gets you a nice fluffy cake. So the next stage is setting. This is when it starts to solidify. So the proteins that we've talked about coming in from the egg, they start to denature, they unwind and they form this kind of gel. The starch that you find in the flour also starts to absorb all the water in the mixture and again swells and it forms another kind of gel. This is also the point where the gluten starts to lose elasticity. So as all of this happens, the cake starts to solidify and it sets in its shape. Yeah. And the third and final stage, browning, this is what happens when the surface starts to dry out. Yeah. And then what's quite interesting is this, this browning process is caused by something called the may-lard reaction. Oh, yeah. And this is a chemical reaction happening between the amino acids in the protein and the sugar. And that's what gives this lovely flavour of browned food. So it's not just with cakes but other foods that you brown. So all of this happens at temperatures above 140 degrees Celsius. If you go much higher, then what happens is you get caramelisation instead. And that happens with the sugar. So it causes that kind of caramelisation of the sugars. And if you cook something like onions, so you learn that lovely smell that you get with onions. But if you cook them perfectly, you can actually get them to taste quite sweet because you can caramelise the sugars inside them. And that gives something called an umami taste. Okay. Right. Hold your horses. Yeah. What is an umami taste? And am I terribly uncaltered for not knowing what that is? Well you were taught probably at primary school that there were maybe four different tastes that you might get in the mouth. Yeah. So sweet, salty, sour and bitter. That's right. Well actually there were five. So umami. Yes, that's what I'd say. That's what I'd say. Yeah. So umami is actually the fifth flavour or the fifth taste. Oh, okay. Um, and it's called umami because it was discovered in Japan back in the early 1900s. And it means kind of pleasant, savoury flavour. Oh. That's kind of the meaning of the word. Um, yeah. So your taste buds can actually detect umami. And on that note, now that I'm really hungry, that's about all we've got time for for our first episode. Yeah. And I think we need to have a look at the list of words and see how many you spotted. Absolutely. So yeah. So, good now. Hmm. I wish to slip soggy bottom in there after you're on in the episode and moist. Mm-hmm. A little bit of leakage from those pies. And of course, a voluminous stiff peaks. Ah, it's my favourite. This may. A little bit later on, a creamy. Yep. And we've got baking tent, rise and beating. We have. That's quite a few. I'm quite pleased with that. Now we'll be back next week with another episode of Small Screen Science. But until then, you can keep in touch with us and see all of the things that we've talked about in this episode on our social media. Yeah, absolutely. So if you want to go to Instagram, we are, we are at Small Screen Science pod, Twitter, at Small Screen Science. Email, Small Screen Science at GMO.com and Facebook, Small Screen Science podcast. And obviously, if you've enjoyed this episode, we'd love for you to subscribe. Leave us a nice five star review and we'll see you next week. Yeah. Bye-bye. [Music]