▲ Assorted pancakes, which are fried in a well-heated pan with oil, are a staple food on the table during holidays. The ‘oily taste’ that fills your mouth with one bite is attractive. ⒸPixabay
A holiday without ‘distancing’ has arrived for the first time in three years. The memories of the short Chuseok holiday are the leftovers in the refrigerator. Just before Chuseok, the Sungkyunkwan Ritual Establishment Committee announced the ‘Standard Draft for Orders’ and recommended that there be no need to send the exhibition. This is because it is not polite to use fatty food for ancestral rites, and it is not necessary to fry in oil or place earthquake food on the table.
Even if it has nothing to do with ‘yes’, various kinds of jeon are an indispensable highlight of the holiday table. The taste is different depending on the ingredients such as Dongtaejeon, Yukjeon, Gochujon, and Donggrantin, but the oily taste that fills your mouth when you take a bite stimulates your appetite. Why do we keep reaching out our hands before freshly baked, forgetting the heat?
Chemical reactions that determine the flavor
Flavor of food is determined by both taste and aroma. It is the same reason that COVID-19 patients with reduced olfactory function say that when they eat food, they can’t know what it tastes like, so their appetite has dropped. As before, in the process of cooking at high temperatures, a lot of flavoring ingredients are created. Because of the ‘Maillard’ reaction.
Jeon is cooked at a temperature of about 200℃, and as the pancakes are roasted, the color deepens, crispy, and the flavor comes alive. When proteins and carbohydrates in food are heated, their taste, color, and aroma are created, a process called the Maillard reaction. It was discovered in 1912 by the French chemist Louis Camille Maillard, and this discovery scientifically proved that food has a umami taste at high temperatures of 120°C or higher. ‘2AP (2-acetyl-1-pyrroline)’, a chemical that smells like popcorn, is a typical fragrance produced by the Maillard reaction.
▲ The crispy tip of large-sized pancakes, such as kimchi pancakes and pajeon pancakes, is the best part. The moisture contained in the gluten film composed of wheat evaporates and becomes crispy. The relatively thin tip is more crispy. ⒸPixabay
The crispy texture stimulates the taste buds when you eat a freshly baked jeon, attracted by the ‘festival smell’. Crispy on the outside and moist on the inside. Gluten is an insoluble protein component in wheat flour, and when flour and moisture meet, a gluten film is formed on the surface. When you place the jeon on a hot pan, the moisture contained in the gluten film evaporates. A hole is drilled in the place where the moisture has escaped. This structure gives us a crispy texture. The relatively thin tip part has a higher specific gravity of the hole, resulting in a crisper texture than the central part.
Fatty foods are attracted to the ‘secret passage’ between the gut and the brain.
If you continue to eat jeon with a savory flavor, you will come across ‘Rapidly Steamed Meat’. Even if you eat just a few calories before cooking with oil, it is equivalent to a bowl of rice. I would blame the taste for making me eat oily food over and over, but there is nothing wrong with my taste. Recent research suggests that the attraction to fatty foods is in the gut, not the taste receptors on the tongue.
Researchers at the Zuckerman Institute at Columbia University in the US provided the mice with oil water containing soybean oil and water with a strong sweetener. The mice initially drank both waters, but within a few days they found mostly oily water. A preference for oily water continued even though the rat’s ability to taste was eliminated by eliminating taste receptors. There’s something else that makes you prefer it even when you can’t taste it.
To find something, the researchers fed mice fat and measured brain activity. Neurons in the caudate nucleus high speed pathway (cNST) in the brainstem were activated. The signal that stimulated the caudate nucleus was initiated in the intestine. The intestine sent a signal directly to the brain via the vagus nerve when the fat component was inside.
▲ American researchers analyzed that the gut has a ‘secret pathway’ that transmits preferences for fatty foods to the brain. In the figure above, the vagus nerve, which transmits signals to the brain, is expressed in blue, and the cells responsible for fat preference are expressed in green. ⒸColumbia’s Zuckerman Institute
The researchers then discovered two types of cells that transmit a response to fat in the gut. One type responded to essential nutrients such as sugar and amino acids as well as fat, while the other responded only to fat. When the researchers blocked the signaling of these cells, the vagus nerve stopped responding to fat in the intestine. Then, when neurons in the caudate nucleus were inactivated, the mice lost their appetite for oily water.
Interestingly, the part of the brain that responds to fat is the same part of the brain that responds to sugar. In a study published in Nature last year, the researchers found that the tail nucleus high-speed reactor is activated even when there is sugar in the intestine. In this study, the researchers gave rats sugar water and sweetener water, but when they drank the sweetener water, the caudate nucleus was not activated. This is the reason why diet sodas such as ‘Cola Zero’ cannot provide perfect satisfaction.
Although it is still at the level of animal testing, the reason people like sugar and fatty foods is that these molecules transmit signals to the brain through a ‘secret passage’. A neurological basis was discovered that made it difficult to suppress the sweet and oily taste.
Can oil taste be recognized as ‘the sixth taste’?
▲ Oil taste is a candidate for ‘6th taste’ following sweet, sour, salty, bitter and umami. ⒸPixabay
There is a saying that ‘shoes are delicious if fried too’. It means that no matter what the ingredients are, cooking in oil will make them tastier. Studies on the ‘sixth taste’ of oil taste, that is, the taste that detects fat, after sweet, sour, salty, bitter, and umami, are also being continuously published.
A representative example is a study published in the international academic journal ‘Journal of Lipid Research’ by Professor Nada Abumrad’s team at the University of Washington in 2012. The research team published a study result showing that the higher the number of receptors called ‘CD36’, which recognizes fat molecules in the taste buds on the upper surface of the tongue, the higher the sensitivity to the taste of oil. Because of this receptor abnormality, people who feel less oily in food consume more fat and gain weight.
Fat taste has not yet been recognized as the sixth taste. It is still competing with various candidates such as water taste and carbohydrate taste. The umami taste was first proven by research in 1908, but it was not until 1985, 80 years later, that it was recognized as the fifth taste. We don’t know how many festivals will repeat until the protagonist of the sixth taste is decided, but we should focus on overcoming the lure of the intestines to attract fatty foods each holiday.
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