 Have you ever noticed how dosa looks so perforated or idly too for that matter? What about bread? You've probably seen those large holes inside of it, right? What if I tell you that the holes in idly and dosa and the holes that you find inside bread, they are all made by the same thing? Yes, they are all made by carbon dioxide. Wait, what? How? Well, let's dive a little deeper and find out how can carbon dioxide possibly make holes inside of food. Microbes have done wonders for the dairy industry, but their contribution also extends to idlies and dosas and the entire world of bread. Let's start with our idly and dosa first. The dough for idly and dosa, we commonly call this dough as the batter. This batter is made up of rice and black lentils or black gram dal. So this is rice and this is black gram dal. This dough or batter is a combination of the rice and black gram dal as we just said and these ingredients, this rice and black gram dal or lentils, they have a load of naturally occurring microorganisms, especially the lentils. Lentils are leguminous plants and these legumes, they have a very special alactic acid bacteria in them called leuconostoc, so you see this bacteria over here. This is leuconostoc. Once these ingredients are soaked, ground and mixed together, we let this batter sit throughout the night. And that is when the magic aka the breakdown really happens. So what leuconostoc will go ahead and do, it will break down all of the starch which is present in this batter and it will break it down into lactose with the help of its huge arsenal of enzymes. So we go from starch to lactose with the help of a ton of different enzymes. Now once leuconostoc has the lactose with it, it's going to go ahead and convert this lactose into lactic acid and along with this lactic acid, it's going to go ahead and produce two more things. It's going to produce ethanol or alcohol and it's going to produce CO2 which is carbon dioxide. Now this is a little different from the way lactic acid bacteria produce lactic acid in dairy products. You see lactose can be fermented or broken down in more than one way. In dairy products like curd or cheese, almost all the time lactose is broken down into lactic acid only. There will be no byproducts to that. Here however in idlies and dosas, not only we have lactic acid with us but we also have ethanol and carbon dioxide. And this carbon dioxide, it increases the volume of the batter almost by three times. And you can actually see the tiny bubbles over here inside the batter. So if you ever decide to make idly or dosa batter at your house, you can actually spot these tiny bubbles. When you steam the idlies or make your dosas, these carbon dioxide bubbles they will pop and leaving behind that perforated appearance that you see in the dosas and the idlies. Now the carbon dioxide is popping. What is happening to the rest of these things, right? So ethanol will evaporate when you cook either of these things. The only thing that does remain is the lactic acid. This lactic acid will improve the taste, the flavor as well as the nutritional value of this entire food. This acidic environment, so lactic acid creates this acidic environment as well, right? This acidic environment also encourages the growth of yeasts. Now these yeasts, they will also aid in the process of fermentation. But this isn't exactly where the yeasts truly shine. Yeasts are the true superstars of the baking industry. They are used to break down the sugars which are present in the wheat dough and to give us a fluffy loaf of bread. But what does this have anything to do with carbon dioxide holes? Well, pretty much everything. Bread dough is made from wheat or flour to which you add a bunch of these yeasts and you knead them with a lot of water to get this dough over here. So we start off with some wheat or flour and to that we are going to add a bunch of yeast. Then we'll add some water to this mixture or this combination and we'll knit them into this dough over here. Now this yeast, this yeast, a very specific yeast is actually used for the industrial production and that is called masacaromyces cerevisia, I'll just quickly write it down. It's called saccharomyces cerevisia. So this yeast and different types of yeasts like this, this one is the industrial standard or the industrial source that we have right now for the baking industry. So yeasts like this, what they are going to do is they are going to break down the sucrose that is present in this wheat dough. So we go from sucrose and this gets broken down by the enzymes that the yeast has and this will end up giving us alcohol, which is ethanol in this case and carbon dioxide along with that and we have enzymes over here. So this yeast is going to break down the sucrose into ethanol and carbon dioxide. This carbon dioxide gets trapped within this wheat dough right over here and the bread rises or the dough ends up rising or fluffing up. Now the question is that why is this carbon dioxide getting trapped, right? It could have gone out, there's no issue with that but why is it getting trapped over and over again? So wheat dough, it has these proteins called gluten. Now this gluten is kind of like a bubblegum, it's a very stretchy elastic network of proteins that is present in this wheat dough and it is not porous at all. So as the yeasts produce more and more carbon dioxide inside the dough, the carbon dioxide it kind of goes out in all directions trying to find an exit, right? So all the purple arrows are the carbon dioxide trying to leave the dough but they're still looking for an exit. But because of gluten which is pretty stretchy and it's not allowing them to go out but it's making sure that there is enough room for all the carbon dioxide molecules that are getting produced but never an exit, always more room but they just cannot leave. So the carbon dioxide ends up getting trapped inside with nowhere else to go because the gluten is not letting that carbon dioxide to leave. That is why this bread is going to puff up like a puffer fish. Once the dough has risen to our favoured height or we see like it's pretty much ready, we are going to go ahead and bake it in an oven. When you do that the dough will get hardened completely kind of like a boiled egg, so how the boiled egg hardens up, right? So this dough it's going to get hardened up as well. Now the carbon dioxide pockets will remain inside but all the alcohol which was produced the ethanol all of that will be evaporated away when it is getting baked. So because the carbon dioxide pockets they still remain when this baked bread is done and when you cut it open you will see these large holes inside of it where the carbon dioxide was originally trapped. And it is this carbon dioxide which is going to make the bread so fluffy and airy and light. These yeasts are pretty amazing aren't they? But what if you cannot tolerate these yeasts? What if you break out into hives every single time you take a bite of bread or you end up having some kind of stomach ache or indigestion? What then? What will you do then? Well you can opt for yeast free breads. So in yeast free breads instead of using yeast they end up using lemon and baking soda. This is for yeast free breads. Now yeast free breads they end up using lemon and baking soda. You might ask me this question that hey will we not see the characteristic large holes in the carbon dioxide pockets that we saw earlier? Well absolutely you will because the reaction between the acid in the lemon which is citric acid and if citric acid reacts with the baking soda it will give you carbon dioxide. So yes carbon dioxide will also be produced even if you are not using yeast but only if you are using lemon and baking soda. In that case this carbon dioxide will again once again get trapped inside the dough. The bread will rise and you will have fluffy airy bread once more. Just not having to worry about getting an allergic reaction or a stomach ache. Maybe you should try having one of these breads you know and compare them for yourself and see what they actually look like. Eat an yeast free bread or a normal bread and also try out the idlies and dosas and you will be able to see all of these perforated holes which are made by none other than the carbon dioxide produced in them.