The story of Korean seaweed, a crystallization of flavor and nutrients

Seaweed (gim - 김) has been an important part of the Korean table for a long time, as it is a delicious and nutritious food. Seaweed is also one of the top two items competing for Korea's seafood exports along with tuna. Once called 'black paper' and hesitated to eat seaweed, Westerners are gradually gaining popularity as a snack with low calories and rich in trace nutrients.

Gim is the most harvested and consumed seaweed in Korea. The product is the seaweed that is black in color and shiny and turns crispy when roasted. Dried seaweed in the shape of paper is usually sold in bundles of 100 sheets. ⓒ Topic

Seasoned seaweed is one of the most popular rice side dishes for Koreans. Dry the seaweed with sesame oil or perilla oil, sprinkle a little salt, and bake it over a low heat, then cut it into a suitable size and wrap it with rice. These days, olive oil is also widely used.

There is a saying that everyone knows what is delicious. This is a story that fits perfectly with seaweed. There are about 70 species of seaweed belonging to Porphyra, and most of them are used as food ingredients in the areas where they grow. Because it's delicious.

You can also seaweed attached to rocks on the coast of Wales, Scotland, and Ireland. Laverbread is a delicious food with the nickname 'Welsh caviar', and it's still a popular breakfast menu for people there. Laverbread is made by boiling finely chopped dolgim for a long time, making it like a puree, coating it with oatmeal flour, and frying it in bacon fat. Laverbread is far from the general shape of bread, but maybe it got that name because it is a staple food for coastal people.

In Korea, rice is wrapped with seaweed that is thinly spread and dried. Dry seaweed is lightly roasted over a low heat, or coated with sesame oil, perilla oil, or olive oil and sprinkled with salt and roasted. The sound of crunching when you put thin seaweed in your mouth and chew stimulates your appetite with hearing. 

Besides, roasted seaweed is finely crushed and topped with stir-fried vegetables on noodles or sprinkled with sesame salt on rice balls. Gimjaban, which is seasoned with soy sauce and made salty, is also a popular side dish, and gimbugak, which is coated with glutinous rice flour and fried, is also eaten as a snack. Gim soup, which is boiled with fresh or dried seaweed in water and seasoned with sesame oil or perilla oil, is also a delicacy.

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In Japan, too, dried seaweed in the shape of paper is enjoyed. Especially, seaweed is one of the important ingredients for making sushi. You can also see scenes where thick roasted seaweed pieces are placed on ramen. On the other hand, in China, round and flat-dried seaweed lumps are torn off and used as soup or stir-fry ingredients.

Kimbap is made by spreading white rice thinly over seaweed and topping it with blanched spinach, carrots cut and stir-fried in long strips, pickled radish, minced beef stir-fry, and egg omelet, and rolling it round. Nowadays, the ingredients and shapes are diverse according to one's taste and preference.

In spring, when seaweed becomes stale and the taste deteriorates, it is coated with glutinous rice paste, dried, and fried to make seaweed crackers. © Court Cuisine Research Institute

Trio of flavor (감칠맛의 삼중주)

There is a Korean joke that "It's cheating to put seaweed powder in soup food" (국물 음식에 김 가루를 넣으면 반칙). This means that seaweed has the power to make food taste good. As it turns out, seaweed has a reason to be delicious. 

The representative ingredients that make the flavor of food are 'glutamic acid', well known as MSG, 'inosinic acid (IMP)', 'guanylic acid (GMP)', which are called nucleic acid-based seasonings. MSG is abundant in green onions and kelp, which are mainly used in the East to create flavor, and onions, carrots, and tomatoes, which are often used in Western cuisine. Inosinic acid is rich in beef, chicken, chicken bones, and anchovies. Guanylic acid is abundant in mushrooms such as shiitake, porcini, and morel.

But seaweed contains glutamic acid, inosinic acid, and guanylic acid. The trio of umami flavors that they play together is not addition, but multiplication. Adding just one inosinic acid makes it possible to feel the umami taste at 1/60 of the usual glutamic acid concentration. If you add guanylic acid to this, the umami enhancement effect is explosive. So seaweed is the epitome of umami. Not only that, seaweed also contains various free sugars, which make it sweet and delicious.

"It has roots attached to rocks, but no branches, and spreads widely over the rocks. The color is purple-black and the taste is sweet and good." (“뿌리가 돌에 달라붙지만 가지는 없어서 바위 위에 넓게 퍼져 있다. 색은 자흑이며 맛은 달고 좋다.”)

This is a description of purple laver (seaweed) from Jeong Yak-jeon (1758-1816)'s "Jasan Eobo", the first marine life encyclopedia in Korea. The description of the shape, color, and taste of purple laver, or seaweed, a red algae with long and wide leaves that grow attached to rocks like roots, is accurate. Seaweed that grows fast has a shiny surface and absorbs light with pigments such as chlorophyll, carotenoids, and phycobilin, giving it a dark red color. When roasted over fire, the heat-sensitive carotenoids and phycobilin are destroyed and only chlorophyll remains, revealing the hidden green color.

Seaweed contains glutamate, inosinate, and guanylate. The trio of these substances create a savory symphony that is more than just addition, but multiplication.

Rich in micronutrients (풍부한 미량 영양소)

Seaweed is also an excellent food ingredient in terms of nutritional composition. Dried seaweed contains 42% protein and 36% carbohydrates, but the amount is not enough as a protein source. Eating one sheet of dried seaweed (3g) a day only accounts for 2% of the recommended daily protein intake. However, seaweed is rich in micronutrients such as vitamins and minerals. Compared to terrestrial plants that grow rooted in soil, the mineral content of seaweed is about 10 times higher.

Seaweed is rich in beta-carotene, vitamin C, vitamin E, as well as vitamin B12 and iron, omega-3 fatty acids, which are easily deficient in people who mainly eat plant-based foods. It also contains enough iodine to prevent deficiency, although the amount is lower than other seaweeds. This is also why seaweed was considered a herb in the past in Britain. 

Mothers in Wales used to teach their children, "If you don't want your neck to swell like a Derbyshire person, you have to eat seaweed bread." (“더비셔 사람처럼 목이 붓지 않으려면 김빵을 먹어야 한다”) This is a story based on the fact that many people in Derbyshire, an inland area of Britain where seafood consumption was low, suffered from goiter (derbyshire neck) due to iodine deficiency.

Recently, there has been active research on the functional effects of porphyran, a polysaccharide component rich in seaweed. Porphyran is a substance that fills the space between the cells of seaweed and plays an important role in protecting seaweed from drying out during low tide. 

Seaweed mainly inhabits the coast where the difference in tide is relatively large. At high tide, it has to protect itself from salty seawater, and at low tide, it has to survive in a harsh environment where it is exposed to ultraviolet rays and air. Depending on the situation, it can lose up to 95% of its moisture, which means that the environmental change is drastic. At this time, porphyran holds the moisture and prevents the seaweed cells from drying out, and maintains the flexibility of the cell wall so that it can survive in both extremes of high and low tide.

However, when this component enters the human intestine, it acts as a dietary fiber, reduces the incidence of cancer, and helps regulate immunity. In addition, various antioxidants that are produced in seaweed to protect itself from oxidative stress caused by exposure to ultraviolet rays during low tide are also expected to have beneficial effects on the human body.

Pile cultivation is only possible in the coastal sea where the difference in tide level is large, but buoy cultivation, which floats buoys and hangs seaweed, is possible in the far sea, which greatly increases seaweed production.

Cultivated seaweed is usually harvested and dried several times from late November to February of the following year, but nowadays it's mostly dried in a dryer at a factory. The traditional method of natural drying in the sun is gradually disappearing due to the large amount of labor required.

Development of artificial cultivation methods

Seaweed is a great food in terms of taste and nutrition, but it has not been long since it was cultivated and eaten as it is now. Gim cultivation is basically a way of imitating nature. That is, gim spores are attached to oyster shells or branches made of wood and planted in the mudflat, mimicking the way gim grows on rocks or shells. The pillar-type cultivation, which fixes the pillars and hangs the gim so that it is submerged in water during high tide and exposed to air during low tide, is a direct imitation of the way rock kim grows on rocks. 

Gim cultivation started in this way in the shallow seas of Korea, Japan, and China in the 17th century, but it was difficult because they didn't know how to sow seeds. They didn't know how gim, which disappeared in the summer, reappeared in the late autumn, so they had no choice but to wait for the naturally occurring conchospores and use them as seeds. 

However, in 1949, Kathleen Mary Drew-Baker, a British algaeologist, studied the life cycle of gim and revealed that Conchocelis rosea, a species of algae that was considered a separate species until then, was actually a stage in the life cycle of gim. She made a breakthrough in the artificial harvesting of gim. Thanks to Drew-Baker's research, the productivity of gim cultivation improved remarkably, and harvesting, which depended only on the sea, became artificially possible on land. In Uto City, Kyushu, Japan, they called Drew-Baker the "Mother of the Sea" and held a ceremony to honor her achievements for making large-scale cultivation of gim possible.

Since then, more stable mass cultivation has become possible with the frozen net method, which attaches spores to a net and freezes it until needed, and then installs it in the sea. Before, pillar-type cultivation was only possible in the nearshore where the tidal difference was large, but with the development of buoy-type cultivation, which floats buoys and hangs kim, cultivation became possible in the far sea, and the production volume increased greatly. 

Korea is one of the world's three major gim-producing countries along with Japan and China, and far ahead of the two countries in terms of exports. Gim produced in Korea is exported to more than 100 countries around the world, including Europe, America, and Africa, and is also called the "sea semiconductor". 

Recently, various types of seaweed snack products have been developed and ranked first in the field of seafood exports in Korea. However, gim cultivation still requires a tremendous amount of labor and is an extreme job, and the global market will demand more diverse products.

Popular food all year round (사계절 인기 음식 )

Gimbap, which is made by spreading white rice thinly over seaweed and then cutting it, and then placing various colors of stir-fried vegetables, sliced pickled radish, ham, and egg omelet in the center and rolling it up, is one of the most favorite lunch menus and popular snacks for Koreans. The rice and various ingredients wrapped in shiny black seaweed create a fantastic taste in the mouth. 

Every time I eat gimbap, I am moved by the fact that the food we enjoy today is the result of the world's people exchanging and helping each other with knowledge and information over a long period. That's why seaweed is a more delicious food.

(Source / Jeong Jae-hoon (鄭載勳), pharmacist, food writer)