If you've been anywhere near the internet lately, i'm sure you've watched or seen content related to the new Korean cooking show – Culinary Class Wars! Like many of my colleagues and me, you probably binged it and completed the series in a matter of days.
From Napoli Matfia to Chef Edward Lee, we've seen greatness in the form of the most creative, tantalising and mouth-watering dishes. On the menu, we were treated to Choi Hyuk Seok's halibut seaweed soup, the Dim Sum Queen's (Jung Ji Sun) crispy mala cream shrimp dish, Edward Lee's tteokbokki gochujang caramel dessert and even bibimbap with some song and dance (and not to mention some sick drum beats).
And... as always, with cooking, there's chemistry! In this blogpost, we'll be discussing the chemistry behind some of the dishes featured in the Culinary Class Wars, namely (drumroll please):
Jung Ji Sun's Basi vinegar meatballs
Chef Edward Lee's tteokbokki gochujang caramel dessert
Napoli Matfia's risotto
Hidden Genius' aglio e olio
The Science of Sugar: Basi Vinegar meatballs and Tteokbokki gochujang caramel
Notice something common between Jung Ji Sun's Basi sugar strands and Edward Lee's gochujang caramel? Yup, they are both made from caramel, which is basically a mixture of sugar and water heated until it turns into this rich, yummy, golden-brown sauce.
Let's talk a little about sugar and caramel. These are some of the various stages of sugar syrup formation:
At 107°C, we have the thread stage. When put in ice cold water, the sugar syrup forms threads. Following that we have the soft ball stage, which is used to make things like chocolate fudge. The firm ball stage can be used for gummies, the soft crack stage for taffies and the hard crack stage for lollipops, and so on and so forth.
The crucial temperature for caramel is 165°C, where the sugar syrup starts to brown beautifully.
The difficult part, however, with making Basi sugar strands or a gochujang caramel sauce is with temperature. The temperature of the caramel has to be very precise – too cold, and the caramel will harden prematurely and not flow. Can't be dipping your tteokbokki icecream in hardened caramel too. Too hot, and the caramel will be too runny, dripping down in droplets instead of forming nice, consistent strands of Basi. In order to form Basi, you need the caramel to first fall in one continuous strand without breaking (see photo from Joanne Chang's lecture: "The Science of Sugar" below). Then only, can you start flicking it with forceful motions to create the Basi strands.
@latenightanna (below) tried re-creating the dish on Youtube. She managed to construct beautiful Basi strands from caramel, after a few trials and errors. (By the way, if you're wondering what "Basi" means, it comes from the mandarin word 巴斯, which means to pull silk, or to pull strands.) To get these strands successfully, you have to flick the caramel pretty forcefully or shake while letting the caramel fall from a metal tray. As the caramel falls, it cools down in air and hardens to form these silky strands of beauty.
As she mentioned, the tough part was getting the caramel not to harden. How can we use Chemistry to solve this issue?
We can add cream of tartar (potassium bitartrate) into the caramel. Cream of tartar, being a weak acid, breaks down the sucrose in caramel into its simpler sugars, glucose and fructose, in the presence of heat. Guess what type of reaction this is... (drumroll again)
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Acidic hydrolysis! Hope you got that right! Glucose and fructose, being smaller sugars, tend to stay dissolved in solution more easily. The presence of these two monosaccharides creates a solution that resists crystallisation, preventing the sugar from solidifying into crystals as it cools.
The Science of Starch: Risotto and aglio e olio
Starch is in both rice and pasta. What role does it play in enhancing the flavour and texture of risotto and aglio e olio?
Well, let's find out! When making risotto, a special kind of rice, arborio rice is used. Now, short-grain japanese sticky rice or long-grain thai rice, no matter how delicious, will not work for the purposes of risotto. Why only arborio? you may ask.
Rice contains a large amount of starch and starch itself is made up of two different molecules: amylose & amylopectin. Amylopectin is a large complex chain of sugars and is a pretty bulky molecule, whereas amylose is a straight, linear chain of sugars.
All rice varieties contain a different ratio of amylopectin and amylose and this influences the stickiness of the rice once cooked. A high amylopectin content (thus low amylose content) makes the rice more sticky and gluey than a high amylose content which makes the rice more loose. This is because the complex chains of amylopectin are hard to loosen once they hook onto each other and are intertwined, whereas the linear chains of amylose can still be separated rather easily.
This ratio also impacts the amount of moisture absorbed by the rice. A rice higher in amylose content absorbs more moisture during cooking. This is desirable for risotto.
To make a good risotto, you’d want an intermediate amount of amylose in there. Too little amylose, and we get excessively sticky risotto. Too much, and we will not be able to form that silky smooth, creamy texture. Arborio rice has the perfect amount of amylose for risotto.
Emulsification
Andddd...what was all the fuss with Napoli Mafia's dramatic mixing moves? (watch video below) Was that all for show, or did that do anything to build the risotto's texture?
This process of intense mixing is called mantecare, an italian technique often used in risotto, pasta or gnocchi dishes to form a creamy and smooth texture at the end of the cooking process. Notice that in the video, Napoli Matfia used the word "emulsification", which we are going to learn about here.
In making risotto, we have ingredients that dissolve in water (chicken stock, white wine) and butter, which is essentially fat. This essentially forms two layers, the water layer and the fat layer. These two layers are immiscible, or simply put, cannot mix with each other.
If you've tried mixing oil and water together, you will notice that they don't mix. Oil, being less dense than water, rises to the top. Even if you stirred the mixture up with a spoon, the oil and water layers will still separate after a few minutes. Or, even if you used a centrifuge and mixed it up real good, the two layers will eventually separate, given enough time. This is because the hydrogen bonds between water molecules are stronger than the instantaneous dipole-induced dipole (id-id) interactions that water molecules can potentially form with the oil molecules. Why would the water molecules want to break these strong hydrogen bonds to form weaker bonds with the oil molecules? There is no "incentive" for them to do so.
Now, a risotto with separated fat and water layers will definitely not be appetising. Just imagine drinking oil and water together... that's just... horrid. While I don't have a photo of a failed risotto with separated fat and water layers, we can imagine what it'll be like with mayonnaise (left) or lotion (right):
eeeurgh! Gross. So, our goal is to find a way to not just mix fat and water, but to keep them together, even if they don't "like" to be with each other. We want to create an emulsion – a stable mixture where fat and water bind together and will not separate! Well, eventually, the mixture should still separate into two distinct layers given enough time, but we want it to be stable enough to hold for a sufficiently long period for us to consume and enjoy. This stable emulsion will give our risotto that palatable smooth and creamy texture which we all love.
So how does the starch in risotto and the intense mixing in the mantecare technique give us a stable emulsion?
Starch
Now, we all know that oil and water separates even when we stir the mixture with a spoon. The oil floats up to the top quickly, and we get our separated layers again in a matter of seconds.
Starch is a game-changer here. When we add starch to the mixture, the heavy and large starch molecules weigh down the oil molecules, preventing them from floating up to the surface again. This keeps the oil molecules in the water layer for a longer time, creating an emulsion that is more stable.
This is also why Hidden Genius used pasta water to thicken his sauce and enhance the texture of his aglio e olio. While I don't have a video of Hidden Genius himself cooking, we have @Lennardy here to show us exactly how he did it.
The pasta water added contains starch from the pasta, and like the risotto, the starch molecules weigh down the oil molecules, preventing them from floating up to the surface and keeping them in the water layer. This creates a stable emulsion and therefore, a smooth and creamy finish to the aglio e olio.
Mantecare
Now, imagine there's an earthquake in your city, with buildings collapsing and roads buckling. You will probably take a long time to find your friends and family in all that rubble and debris.
This is like what happens when you vigorously mix the oil and water layers using the mantecare technique executed by Napoli Matfia. Oil and water gets dispersed into tiny droplets which are then evenly interspersed throughout the mixture. The oil molecules, being mixed vigorously with the water molecules, will take a longer time to find their friends (the other oil molecules), thus staying in the water layer for longer. While still temporary, the two layers will stay mixed for a while, long enough for us to enjoy our risotto.
An emulsion formed through mantecare will probably last 1-2 days, but if you want your emulsion to stay stable for longer (weeks or months), a homogeniser is typically used. You can watch an industrial homogeniser at work below:
These homogenisers create really tiny oil and water droplets, interspersing them among each other. They are used to form stable emulsions, such as mayonnaise, that has a shelf-life of about 3 months.
Finally, if you wanted an emulsion that lasted really long, like lotion, hand cream, soap or shampoo that can last for about 6 months to a year, you would need to add a surfactant into the mixture.
Surfactants are molecules that are made up of a hydrophilic (water-loving) head and a lipophilic (fat/oil-loving) tail.
This is really convenient! Because then, by adding surfactants into our mixture, we can get the water molecules to bind to the hydrophilic head, while the fat molecules can bind to the lipophilic tail:
This allows water and fat to bind together, via the surfactant. What a cheat code! Here are some examples of surfactant molecules that are commonly found in soaps or shampoos:
As you can tell, the hydrophilic heads are commonly ions, which can form ionic-dipole interacts with water; while the hydrophobic tails are commonly hydrocarbon chains, which form id-id interactions with fat molecules.
That's all about emulsification for today! Hope you learnt something about the science of cooking :)
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