By Se Ri Lee' 19
In 2017, Mr. Jaehoon Jeong, a pharmacist and food science expert, wrote an article on the science of baking castella. With his permission, I translated his article into English.
I have received permission from Mr. Jeong to translate his article “Great King Castella and Science.” Most of the photos I included are not part of the original article. To access the article, click on the link below.
http://olivem.co.kr/archives/7653
Written by Jaehoon Jeong
Translated by Se Ri Lee
The castella from Taiwan [Great King Castella] is still leading the trend. The causes of its popularity and the story of the science hidden behind Great King Castella.
Great King Castella Comes From Taiwan
Even people with strong opinions often don't know what they like and dislike. For me, this was the case with Great King Castella. I disliked waiting in long lines--not only because I wasted so much time waiting but also because I had to eat in such a hurry. What about this castella was so different that people were willing to wait so long to eat it! I thought it wouldn’t be any different from other castellas--at least, that’s what I thought initially.
But one day, I decided to wait in line to try Great King Castella. There happened to be not many people in the mall that day, so the line was pretty short. I gained my appetite when a sheet of freshly baked golden castella came out of the oven. My mouth watered as I watched the chef flip the castella, peel off the parchment paper, flip it again, and slice it into small, even pieces, as he made accurate measurements with a metal ruler. The moment I touched a piece of warm castella, I was dazzled. Already half of it was gone in an instant. Would a fox who had complained grapes were sour (when it was not able to reach them from the tree) have felt the same way when it was finally able to taste them. That day, I realized I didn’t dislike Great King Castella. Only waiting in line, I knew I disliked.
The Science of Castella
Once you try Great King Castella, you’ll understand why it is everyone’s favorite. It’s just like foam. We typically dislike nitrogen gas in food packaging, but we like air bubbles trapped inside foam. It’s surprising how well eggs could form such foam-like texture. Strictly speaking, what is able to stabilize the foam wrapping the air bubbles is the protein that makes up merely ten percent of egg white. The remaining ninety percent--water--is not capable of stabilizing the foam at all. This is why when you shake pure bottled water, bubbles disappear quickly after they form. But by beating egg white, you’re loosening the protein molecules that were once bound together like a woolen ball, allowing them to rearrange themselves in a net-like structure. These protein molecules increase the viscosity of the liquid surrounding the air bubbles, and the net-like structure of these molecules keeps the air bubbles and water in position. This is why you can make foam by beating egg white, for the egg white can expand to eight times its initial volume.
Without any outside effects, the egg white would soon contract back to its normal size. With the addition of heat, however, everything changes. Heat prevents air bubbles from disappearing by allowing strips of protein to form tight chemical bonds (“hands”) with each other. The “hand” hidden among these protein strips is the sulfur atom. If heat is applied to the egg white in the oven, the sulfur atoms in protein would chemically bond with each other, forming what is called a disulfide bridge. Then, if the protein molecules coagulate, the liquid foam would solidify. The foam would expand even more because of the water vapor formed by heating, but the sugar and flour in the castella dough would keep the castella from collapsing and losing shape.
The difference between what we like and dislike is subtle. We like how disulfide bridges allow protein molecules to coagulate. Though I could deny I asked, it is true that the process of cooking eggs, whether it be boiling, frying, poaching, or making an omelet, entails chemical coagulation. The fluffiness of Great King Castella is due to the sulfur atom as well. But we dislike it when the castella’s overcooked, when the disulfide bridges break, when the sulfur atoms escape. Because we dislike the smell of rotten eggs characteristic of sulfur.
Cooking Is Chemistry
There are many who dislike chemistry but love cooking. But cooking is chemistry. We don’t line up to buy eggs, sugar, and flour. We line up for the final product--a mixture of eggs, sugar, and flour inflated with air bubbles. The minimal difference in preference that determines what people like and dislike is indeed caused by the difference in the presence of a chemical element. We like the air bubbles trapped inside castella, but the air bubbles on their own are not enough to make us like castella. Even though there is still air in a piece of dry, crumbly castella, not many people would want to eat it. Texture--the kind that softens and melts down on your tongue--is key; it makes Castella the Great taste vastly different from other castellas, though it may be hard to tell the difference just by their appearances. If the egg white rises and you use a small amount of yolk and a lot of flour, you’ll end up with a castella that is pale in color and dry in texture. As the fat and emulsifier contained in the yolk prevent the foam from being formed, the amount of air that can be trapped in air bubbles decreases, but the yolk still gives the castella a softer texture.
It’s more difficult and costly to use both the egg white and yolk, but the difference in end product is very big. A castella made with a sufficient amount of egg yolk is better than a castella made without in both color, flavor, and texture. This is also what causes people to like some castella stores and dislike others, even though they all hold the same brand name, Great King Castella.
There are those who like Great King Castella and those who like Nagasaki Castella, whose bottom is layered with coarse sugar crystals. The amount of sugar does not only change the taste. It also changes the texture. Although sugar hinders the formation of foam, it helps keep the highly viscous foam from disappearing. Sugar is hydrophilic, so it’s able to prevent too much water from evaporating in the process of baking the castella. The sweeter the castella, the softer it is due to sugars, or saccharides, like honey, starch syrup, or granulated sugar. The golden brown crust of castella is also caused by sugars, as sugars and amino acids react by the Maillard reaction* at high temperatures. However, the Maillard reaction does not occur at the interior of the castella because the temperature does not go above 100 °C, for baking this part of the cake is dependent on water vapor. As you can see, sugar determines not only the degree of sweetness but also the physical and chemical properties of food.
Are the Origins of Food Really Important?
With my opinion only, it’s hard to end the debate. The moment I posted on Facebook a video featuring someone slicing Great King Castella, I received many comments. Whether it was worth waiting in line. Whether it tasted like plain castella. Whether it tasted worse than plain castella. Whether it was better. There are a lot more incidents like these on the Internet. Whether it is castella or not. Whether castella was invented in Portugal or Spain. Although these comments are better than those endlessly debating the amount of sugar and cholesterol castella contains and what their effects are on our health, it is still tedious to debate--excessively--on a certain dish’s country of origin and to assess a dish just by the norm.
Fewer than four hundred years have passed since we began to use the foam-making ability of an egg in cooking. In a relatively short period of time, numerous exchanges of recipes and ingredients have been made overseas, and various methods of making sponge cakes have developed as well. The inconveniences of the egg shortage, caused by the bird influenza outbreak, have shown how eggs have been central to the field of baking over the past four hundred years. It’s uncertain how long the popularity of Great King Castella would last. But it’s certain that the popularity of foamy egg would not disappear like foam. It is fun to taste cakes baked by different methods using the same main ingredients--eggs, sugar, and flour--and to observe the physical and chemical properties of those ingredients and differences created by those different methods of baking. We’re sensitive to nothing but origins. We’re more curious about where the origin of Great King Castella lies, what method of baking is the original, authentic style of making castella than assessing the taste. We're curious only about where this Great King Castella was made. We want to know what the origin of Nagasaki Castella, macarons, tiramisu is, what the traditional method of making them is. Perhaps our picking a standard and seeking tradition stem from our culture’s tendency to separate the victors and losers and to rank people based on power. However, no recipe just falls alone from heaven. Even kimchi--the absolute standard of the Korean culinary culture--cannot be made without the cabbage imported from China, green onions and garlic from Central Asia, and hot pepper from South America.
Don’t get me wrong. Understanding the original form of food and the fundamental characteristics of a recipe is significant; however, obsessing over them never leaves room for invention. I can’t imagine living in a world without Nagasaki Castella or Great King Castella where the coarse, original 17th century sponge cake is considered to be the best form of cake made with foamy eggs.
Quite an imagination I had while taking a bite of this sweet castella. I’ll truthfully admit on Facebook that both Nagasaki Castella and Great King Castella tasted good.
Sources:
http://olivem.co.kr/archives/7653
http://m.blog.naver.com/taekstory/220770153383
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