Instant Genius - Food Science: How to become an expert baker through science

Episode Date: March 30, 2025

Baking can be hard. Measurements need to be exact and techniques perfected. But with the right tricks and by understanding the science of baking, you can become the envy of your friends with the perfect loafs and cakes. Part of our Food Science series, we spoke to Cristiana Solinas. She is the head of the National Bakery School at London South Bank University. She talks us through the science of how to make good sourdough, why your loaves are coming out too dry and busts the biggest science myths in daily baking. This episode is brought to you in association with EIT Food https://www.eitfood.eu/ Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Focus magazine, where we interview some of the biggest names in science and baking can be hard. Measurements need to be exact and techniques perfected, but with the right tricks and by understanding the science of baking, you can become the envy of your friends with the perfect loaves and cakes. Part of our food science series and in collaboration with EIC food, I spoke to Christiana Salinas. She is the head of the National Bakery School at London South Bank University.

She talks us through the science of how to make good sourdough while your loaves and cakes might be coming out too dry and busts the biggest science miss in daily baking. So I feel like there is a lot of questions around baking when it comes to the science of it. One of the questions that I've always wondered personally is how do different types of flowers affect the outcome of different bait goods? Okay, so this is maybe something that not everybody knows.

It's not that we have gluten in flour. You know, you buy flour, it's not that. the package, you know, the gluten comes out. So flour may be different because of a few things inside. One of this is the protein content, you know, just got the protein flour, primarily are in the form of glutenin and gliding. Combined with water and, of course, the action of a mixer or overhand, they form the gluten. So the gluten is the substance that's responsible for elasticity and chewiness of the dough. So the higher the protein content, the stronger the gluten network, which affects the structure of your baked goods. So the protein content of flour

plays a major role in how it behaves during baking. That's why we pick different kinds of flowers for different kinds of products. It's not always the same. I mean, for bread, we need higher protein content for dessert and lighter baked goods, like, be biscuits or sponges, we need less protein content into it. So that's very important. So it's not that you just go into a store and buy any flour and any flour would work for everything. I mean, it does for us because we have the experience and we know that we can also, you know, just play a little bit around that, but not for everyone. And then if you go way more into the science, there's also other things in flour that affect the final product. Could be,

the ash content, which is a little bit more specific to explain. If you want, I can explain what it is. And the amount of damage starches that you can find in a composition of flour. So flower, it's very, very, very, variable. And I think for a lot of people that start baking in the early stages, there's this kind of idea of this really big challenge that is sourdough. Why has it got that reputation for being so hard? You know, you just come right through through my pain. Because sourdough is this, is these things where people think that,

you know, just to make good sourdough, you have to be aligned with the planets or have, you know, special crystals going on top of the dough and things like that. But it is one of the most scientific things that you can think about. So a few years ago, I had this seminar running.

And the title was, the mystery of sourdough case solved. Because, you know, it is very, very important to understand that for most people, sourdough is a mystery, but why? Because, first of all, the term is wrongfully used. I mean, it identifies bread made with a natural starter, but sourdough refers to everything, every kind of dough that is made with a natural starter or a bacteria culture that we also call it. So it is complicated because everybody thinks that there is, like I said,

you know, it's a matter of the temperature of this and that. And yes, these things will influence. But it's basically, it is a process. You know, there are enzymes in it and they work at a different acidity. So it's hard to get it right if you don't know how the process works. Why things happen and how to fix them, right? Because this is what happened. My advice is if you're seriously interested in understanding the process of making sourdough,

sourdough products, not just the bread, you have to avoid listening to 100 of so-called bakers around there and invest in a serious class with the baking professionals. Because it's all a matter of pH, you know, in the dough. So depending on the pH value, the dough behaves in different waves,

both when you need it, but even when you bake it and when it ferments. And it depends on the flour you use. It depends on the water you use. Everybody says, oh, no, it doesn't matter. It doesn't matter. It does matter. And the thing that I hate the most, when people say, my sourdough starter has been alive for 25 years,

no, you have managed to keep your bacteria culture alive for 25 years and get it to reproduce and proliferate. But the starter dies, you know, because if the bacteria don't have any food, they cannot perpetuate. Many things that, you know, people don't understand about sourd. just invest in one professional class and you'll get it. Seek professional help. Yes, exactly.

And I think the main point we've covered already is the fact that small changes, any minute change in baking can make a huge difference. Yes. So I'm interested how effective some of the plant-based alternatives can be when it comes to baking. For example, if you switch out eggs with aquifer. So there is a joke I always make with my student. And I always say that the only thing that can replace one egg is another egg in baking.

So there's nothing else that you can replace it well because eggs are specifically made in a way that they work in baking because of their characteristics, you know, the way they are all the substance that they are in it, the amount of protein, the amount of lecetine and albumin and the water content, fat and all of that. But we have to be open-minded.

And there is actual evidence out there that some plant-based alternative can be used instead of animal products like eggs. In the end, I think it is a method of compromise. Some plant-based ingredients can be used to mimic the structure given to bake products by animal-based ingredients, but it could never be the same. So every ingredient has a very specific chemical composition. And the chemical composition is crucial because it affects things like, I don't know, texture, structure, flavor. Let's say aqua faba, for example, that it's very much used to replace

egg whites. In the end, your product will smell or taste like chickpeas. There's nothing you can do. It is a matter of compromise a lot, yes. Okay. And that touched on another question that I wanted to ask, which is what the role of eggs is in baking and just why they seem to be in almost every recipe that you see. Yeah, you know, just eggs are one of the main ingredients. So they're important in many recipes in baking because they have a unique combination, let's say, of proteins, fat and water. And it makes them, all these percentages of protein, fat and water inside the egg make them one of the most effective and essential ingredients in the world of baking. They contribute to a structure, to texture and to flavor.

For example, the lecetin in the egg yolks is a binder, and he helps holding all ingredients together. For example, the protein in egg whites that's called albumin, coagolate, another word is set when heated, and create a structure that helps give big goods, shape, and stability. So every single ingredient chemical components has a function. For example, we say that eggs are an excellent foaming agent. So they help to create volume of a product, especially when beaten. When you beat eggs, particularly the egg whites, like I would say, you incorporate air into the mixture. And so once the protein gets trapped into this air, coagulates and make, you know, just the batter or the dough more stable.

And with the shape, also flavor because of the fat, of course, you know, the fat in the egg yolks had a creamy, battery taste color because, you know, the fat again in the yolk helps with the browning, which gives cake, cookies, biscuits, bread, desirable golden crust or crumb. You know, when we egg wash at the top of the baked goods and it comes out golden and nice and really just makes your mouth water and other actions like emulsifying egg yolks because of the lecetine would help to mix. Imagine, fat and water, they do never mix. Like oil and water, they cannot combine, but, you know, with an egg, you get this emulsion power that makes them living together, tenderizing. So eggs are really,

really irreplaceable. Like I said, the only thing that can replace one egg in baking is another egg. Everything else is very, we try, absolutely, understanding, because some people have needs of having, you know, plant-based. In my opinion, opinion is a little bit too, I mean, let's just have something else. There are dessert that they are already plant-based. Think about a nice sorbet. Sorbet doesn't have any animal product. It's a lovely dessert. What about fruit? It's personal because for us is a big challenge. Of course. That makes sense. And I'm going to, I'm afraid, quiz you on another thing of removing something from baking. Can you effectively remove gluten in recipes, for example, with gluten-free people? Well, I think there should be

a distinction. Okay. There are recipes in which flour is the main ingredient responsible for the whole structure or the final product, like breads, for example, focaccia's pizza. And the recipe in which flour is only added for other reasons. So gluten-free bread is very hard to replicate because the structure created by the gluten and the way you react when heated is unique. In other recipes, like an egg white-based sponge, for example, what we call a d'acquoise or a joconde,

the small amount of flour added is only in support of the structure mainly created by the egg whites and their coagulation during the baking process. So in this case, the flour is mainly used to balance the amount of water introduced by the egg whites. Composition of egg whites is 95% water. A store-bought gluten flour would also work. But in bread, the gluten network is a network like strand or just put together this way. And the gluten network is really elastic, right?

It just goes, can be extended, can be expand. And when the yeast basically digest the sugars that the yeast eats during the fermentation process, all these little bubbles of gas get trapped in the gluten network. When they get heated, you know, the bread get to a point where it expands. It's nice and it forms that shape. Can you imagine without the gluten network where all this bubble would be trapped? There wouldn't be any place to trap them. So that is why it's really difficult to mimic something that's just the gluten strand.

It's a natural thing that they form. So yes, we use maybe egg whites to give it volume. We used other things like xanum and things that mimic the structure, but it's very difficult to remove gluten in recipes and use gluten-free alternatives because it's impossible to replace it, to make it the same. can mimic, it's okay, but not, never, it's never going to be perfect. It can do a good replication, but it can't match the real thing. Nowadays, yes, you can definitely replicate because there are many things that can be used.

But again, as a baker, and I understand the needs of people, there are things like, let's say, think about Mexico and corn tortillas. It's corn, it's not gluten, and you can have a perfect made tortilla as, you know, just the vessel. Bread is a vessel for something else. You carry the cheese, you carry the ham or an egg or avocado, whatever you like, right? So you can always balance it out. No one goes to Hank's for his spreadsheets. They go for a darn good pizza. Lately though, the shop's been quiet. So Hank decides to bring back the $1 slice. He asks co-pilot in Microsoft Excel to look at his sales and costs. Help him see if you can afford it.

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specialist focal, name audio creates systems that deliver exceptional sound and unforgettable listening experiences at home. Try it for yourself at a focal powered by name boutique. Visit focal powered by name.com for more information. When it comes to baking, I think there's a couple of stages that we're all known and experience and for me it's always been a slight mystery. But why do we have to let those rise, rest, chill, you know, these things. different things in between the stages of recipes. Because that's the reason why I'm here, right? Because baking is a science production of baked goods,

baked goods or other kind of desserts, depend on the chemical reactions of ingredients. So chemical reactions can be influenced, indeed, by time, as the rate at which a reaction occurs often depends on factors like temperature, concentration, and time. So some reactions happen very quickly. while others may take longer to reach completion. Yeah, in baking and pastry,

this is particularly important and relevant because, let's say, fermentation or slow caramelization of sugars or they need time, you know, just setting time of a jellifying agent like gelatin, they rely on time to produce the desired outcome. So you need to be patient. When you bake, you don't have to rush it. So everything is like a chemical reaction.

and chemical reactions need time to happen. They cannot just happen right away. I mean, you put baking soda in water, you can see the baking soda rises right away, right? Makes that sound, especially if you use some acidic with it. But for example, natural yeast or natural starter or this kind of stuff, they need time. You have to imagine the yeast as a human being.

I always say this to my students. So the yeast gets dissolved into the flour. the yeast is really fussy, cannot eat complex sugar, needs only simple sugars, but starches are complex sugars. So the yeast needs to work very hard to get all these starches broken down in simple sugars, then eat them at his own pace, at the right perfect temperature, digest them, produce gas. Same as every other human being, I said. So they like a certain temperature, they don't like the direct light of sun.

So always imagine yourself sitting at the beach, you know, with a nice drink in the shadow. This is how you have to, you know, just in the shade. This is how I imagine. So it takes time. And yeast is like that. And imagine the starches when you put a batter in the oven. You put it in the oven and it only sets when the starches reach 60 degrees Celsius. So they coagulate.

Before that, nothing would work. So it needs a lot of patience. Yeah, and a lot of passion. Another, I guess, stage in recipes that I need your scientific help with is when we incorporate air into cakes or into batters, what is it that we're doing there? So like we said before, when we talked about the egg whites, for example, incorporating air, especially into cakes, there is a distinction, cake or breads. So incorporating air into cakes, it's a very important step to achieve the light texture. When you mix air into a batter, you are creating all these tiny pockets of air that when they're heated, they expand during baking, which this process helps the cake rise and become soft. Essentially, you know, the air you mix into the cake help it rise, achieve the right texture and have a delicate soft crumb.

It's a crucial part of the chemistry of baking. In bread, for example, imagine the yeast as before, as a human being, as a living organ. It needs air to survive. If you make bread and you put them into a vacuum, nothing will happen because air is something that the bacteria and the yeast, let's not talk about bacteria because bacteria is more than sourdough and always good bacteria and ever bad bacteria. But, you know, they need air to survive. So and the yeast is the same. It's a live organism. So air is very, very, very, very important for both processes, both.

in cakes because of the texture and in bread because of the survival of natural bacteria culture or even on the yeast. And we've mentioned yeast a few times throughout this conversation. Is there when it comes to baking advantage or a reason to use fresh yeast rather than an instant or when do you need different types? Well, this is, in my opinion, is very personal. I got trained in a school in Chicago and San Francisco because I'm from that side of the world. Somebody swore to me.

Oh, I can't recognize when you're using, you know, just dry yeast or fresh yeast. I've been in the industry forever and I couldn't tell. So in my opinion, it's a matter of convenience. For example, if you have fresh yeast available in small portions maybe, by your means, use that one because it's good. but if you don't because it's not easy for it to come around, I don't think there's any wrong in you is instant yeast or dry active. The one that lasts the most shelf life, you know, it's very important. The fresh yeast doesn't have a long shelf life.

So you know that if you buy it, you have to use it in three, four days, stop. You cannot freeze it because it loses a bit of strength instead dry active instant. They last forever. We've kind of touched on a lot of these complexities that come with baking. What are, I guess, some of the most common mistakes you see when people talk about baking and some of the things that they could avoid? So it's when they think that they have the talents in their hand. I was like that before.

You know, I want to make a cake. I don't need a recipe. I know how to make it. My grandma used to make it with this. My mom used to make it like that. No. If you don't follow a recipe, if you don't. on-weight ingredients accurately, you know, just the cake or any other kind of dessert will never

turn out. So not following a recipe, not weighing ingredients accurately, or trying to guess or replace ingredients, you know, these are major mistakes. Another one is when they are kneading a high-hydration dough for bread and they keep adding flowers because it's sticky. So you completely unbalanced all the percentages in a formula. So invest in a very good book. Follow the recipe and read the recipe until the very end before starting.

Because that's another mistake that just people often make. That does raise another question that's a personal one to me. I don't know if other people feel the same way. But with the, you know, you're needing a dough and it is very wet, what is the best option there? Do you just have to accept its wetness and push through? Yeah. Okay.

But you know why? Because, you know, if the recipe is wrong, then it's not your fault. But if you have a very reliable book, and that books tells you that if you want to have, you know how these photos on Instagram now, this very airy focacca's with everything is so open, those are high hydration product. But what's going to happen? There are methods that you can follow to make sure that your dough incorporates all that water. First of all, it's an autolise.

So basically, you put the water and the flour together, and you let it rest for a little bit. So the flour is already hydrated, and some of the gluten network is already forming. Then you keep going, and you need, and you need, if you have a mixer, it's even easier. But if you do it by hand, keep going. The more you need, the more the gluten network will form, and the more structure will be, and the water will be all incorporated inside. You can do something just to avoid for you to go crazy because it's too sticky. You can put a little flour on your hands.

This is something I always see in masterclasses adding flour. No, don't. Keep going because the elasticity will make the dough tacky but not sticky. That's a major, major mistake. And on a, I guess, slightly similar note, are there some sort of great science-backed hacks that you can use to improve your baking, things that can just solve some little issues in your kitchen? The thing is everybody thinks that they can cook, right? Everybody think that they can bake. This is a little bit of the problem of our profession. So I have students coming in and telling me that there are TV shows that they follow as it would be a Bible, right? And I understand showbis, I understand, but we are in education. And sometimes, you know, just making our students to understand that there is a lot of science behind it and courses like ours, that's a degree. It's not a fly-by-

course. There is a lot to study. So I think that unfortunately baking has become a little bit of a, it's been for quite a while, a little bit of a trend, especially after COVID and all of that. So the greatest advice I can give if, you know, just buy a very good and reliable recipe book and always follow the recipes without changing anything, you know. Like I said before, weighing ingredients in grams, because grams is very, very precise. And with a scale, possibly. Avoid cups, tablespoon, pinches, eyeball measurements. And the most, most important of all,

always, always read the recipe until the very end. Because the recipe at the very end may tell you, prepare these 12 hours in advance or do this three days in advance. You know what I mean? So these are things that really make the difference. If you have money to invest, take one product you really like and invest those 100 pounds

for a masterclass with someone that will explain it to you. So from that point on, you're on your own and you'll never make the same mistakes. One of the other questions that I had in mind was this idea of flavors enhancing other flavors. You know, you often see something like Guinness in cakes or chocolate and coffee and these sort of like famous combinations. What is it about certain flavors that just match well with each other? I think, I mean, in the end it's very, very. very personal, right? What you like is maybe what I don't like, but there are, like you said,

some people pleaser, like coffee and chocolate together, you know, they're always very much appreciated by people. I think that flavors enhance each other because of the way they interact on our taste buds and through their chemical compounds. Let's say, for example, you mentioned chocolate and coffee. They share some of the compounds, such as earthy tones coming from roasting process because they both are roasted. You know, coffee beans and cocoa beans, they're both roasted. So this similarity is allowed them to blend well together, creating a richer taste experience. The chocolate enhance the coffee and the coffee enhance the chocolate experience because they're both warm flavor coming from the same process. Instead, imagine like

coffee and lemon. Not as nice. A lot of people like it. Don't get me wrong, but for me, for example, Lemon is cold, acidic, coffee is warm and smooth. So together they don't really match. In addition, it could be also a matter of aromas. So aromas come into play a lot because they account for much of what we perceive as flavor. You know, it comes in the nose. So it's really close to your mouth and everything else. So if you imagine the fresh combination of mint and lime, really great.

When you combine this two, the fresh aromas also, you know, just overlap, intensifies, creates a very harmonious experience. Good combination, all we take into account contrast and balance. And something that is very, very important is the variety of texture, something that may be harder or crunchy, together with something that's smooth. So we try to perceive it and always, always ennance everything with a pinch of salt. salt has this major, major role of enhances some flavors. Not too much, of course, but that's also something else.

We have this when students try to make up their own dessert, drag classic combination, apple and cinnamon. Everybody loves them, oh, it's Christmas. Or I don't know, spicy, like ginger, oh, yes, Christmas. So it also depends on what it reminds you of. Thank you for listening to this episode, Vincent Genius. That was Christiana Salinas, talking about the science of baking. The Instant Genius podcast is brought to you by the team behind BBC Science Focus magazine,

which you can find on sale now in supermarkets and newsagents, as well as on your preferred app store. Alternatively, you can come and find us online at sciencefocus.com. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have digital precision with analog warmth. Alongside French acoustic specialist focal, Name creates high-end audio systems combining innovation with craftsmanship,

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