Nori (海苔)

Nori is a general term for edible algae such as red alga, green alga, cyanobacteria (blue-green alga) and so on. Alternatively, it refers to the food products where algae were dissolved in water, picked up, spread like a sheet of paper and dried.

Taxonomic position

(=>See seaweed)

Because the word 'nori' in Japanese originally refers to epiphytic algae as a whole, which live on rocks underwater, like Hepaticae, many kinds of algae that are not edible often have names such as 'XXX nori' or 'YYY nori.'

Taxonomically, edible algae are categorized in mutually distant groups, as follows:

The group belongs to the eukaryote domain Plantae, Rhodophyta, Bangiophyceae, Bangiales, Bangiaceae, Porphyra. Asakusa nori (P. tenera),' 'Susabi nori (P. yezoensis),' 'Uppurui nori (P. pseudolinearis)' and so on are in this group; they're also called 'i-nori (rock nori)' and are processed into 'ita nori' (which is dried nori but not toasted). P. umbilcalis, which is eaten in South Wales, belongs to this genus. Kankoku nori,' or Korean nori, is also processed from this genus.

The group includes the sea lettuce or green laver, which belongs to the eukaryote domain Plantae, Chlorophyta, Chlorophytina, Ulvophyceae, Ulvales, Ulvaceae.

River products
The group is called 'kawa nori (Prasiola japonica YATABE),' which lives in limpid river streams in the mountains of Shizuoka Prefecture, Kochi Prefecture, Saitama Prefecture and so on, and belongs to the eukaryote domain Plantae, Chlorophyta, Chlorophytina, Trebouxiophyceae, Schizogoniales.

River products
The group is called 'Suizenji nori (Aphanothece sacrum),' which belongs to the Bacteria domain, phylum Cyanobacteria, Nostocaceae, Chroococcales, Chroococcaceae, Aphanothece.

Taxonomically, each of them is dramatically different, but 2 and 3 belong to the same green alga and somewhat closely related. Number 4 is widely different from the others, and is not classifiable among normal plants.

Though they belong to different taxonomic groups and their life circles are different, each of them is sufficiently elucidated. As for 1 and 2, by using the knowledge acquired through the elucidation and artificially managing the life cycles, the seedlings can be produced in high volumes and cultured on a commercial scale.

As food products

Here, 1 Porphyra in the former section is mainly described.

Uppurui nori (P. pseudolinearis)' and 'Susabi nori (P. yezoensis)' are used in sushi (nori-maki, gunkan-maki), onigiri (rice balls), isobe-mochi (isobe rice cakes), furikake (powdered seasoning agents), fillings in ramen and so on. Fu nori (cloth nori)' and 'ao nori (blue nori)' are, on the other hand, used as furikake for okonomiyaki (Japanese-style pizza) or osuimono (soup) and so on, as well as onigiri or furikake. They are very often used as foodstuffs in Japan.

Seasoned nori is called 'aji-tsuke nori (seasoned or flavored nori).'
It was developed by the well-established Yamamoto Noriten Company. Moreover, there are 'kizami nori (chopped or shredded nori),' 'nori-no-tsukudani' and so on (laver boiled down in soy, Momoya's 'Edo Murasaki Gohan-desuyo!' in the Kanto region, Isojiman-Bunsen's 'Ala!' in the Kansai region and so on are famous).

Additionally, nori is rich in protein, dietary fiber, vitamins and so on.

Dried nori is sensitive to humidity, so it's stored in a closed container with desiccant agent in it.


Formerly, 'murasaki nori (ama nori),' 'igisu (tengusa),' 'hijiki' and so on were referred to as 'nori.'
Hijiki, in particular, was also used as a glue for pieces of paper because of its viscosity. Nori (glue)' is called as such because, during the Nara period, the 'nori (laver)' was used in gluing together pieces of paper.

As early as 713, it appeared in "Hitachi-no-kuni-fudoki (The topographical records of Hitachi county)," which has the following descriptions about YAMATO Takeru:
According to the old man, Emperor YAMATO Takeru came to the beach and arrived in Nori-no-hama.
At that time, lots of seaweed (locals called it 'nori') were dried on the beach.'
Likewise, in "Izumo-no-kuni-fudoki (The topographical records of Izumo county)," dating from 733, there is a description such as 'murasaki nori, in Tatenui County, is the best.'
The area of Tatenui county is now encompassed within Izumo City and roughly corresponds to Hirata City before the incorporation in 2005, where Uppurui (Izumo City) produces nori as a specialty product.

In Heijyo-kyo, where the capital of Japan was located in 710, there were a market called 'nigimedana' where seaweeds were sold and a market called 'mohadana' where processed nori and kelp like tsukudani were sold. In the 'Taiho Ritsuryo (Taiho Code)' enforced on February 6, 702, nori was collected as a tax (and so February 6 is designated as Nori Day). Thus, nori came to be rooted in Japanese food culture and nori with the specific names, such as 'ama nori (sweet nori)' or 'murasaki nori (purple nori),' appeared in "Utsuho-monogatari (Utsuho Story)" which was written in or around 987.

The birth of 'ita nori'
In the Edo period the cultivation technique was established, the nori (murasaki nori) caught in Tokyo Bay came to be processed into paper-like sheets by using the paper manufacturing technique of 'washi (Japanese paper),' and finally the 'ita nori' on shelves saw the light (contrastingly, undried nori was called 'nama nori (raw nori)'). Though there are various views on 'Asakusa nori,' which is representative of the nori of Edo, the view that put the origin in 1457-1459 at the latest was suggested in "Asakusa nori," a 1909 work by Kintaro OKAMURA.

Food products that used nori were expressed as '磯辺 (isobe)' and the production areas were referred to as '石部,' '磯部,' '石辺' and so on (all are called 'isobe').

The method of cultivation

It is confirmed that the cultivation of nori began during the Edo period.
In the late Edo period, the cultivation technique of nori in Omori (currently, Omori, Ota ward, Tokyo Prefecture) was introduced nationwide by 'Suwa nori syonin (Suwa nori merchants).'
At that time, as the nori's mode of life was unknown and the nori farmers relied on the rules of thumb, nori was called 'un gusa (fortune weed)' due to its unstable yield quantity. However, in 1949 Dr. Kathleen Mary Drew Baker (1901- Septemper 14, 1957) discovered the filaments of nori, thus elucidating the heretofore mysterious life cycle and led to the expansion of the areas in which the cultivation was possible by putting to practical use the artificial collection of seedlings instead of the natural one, which was unstable.

In autumn, when the temperature of seawater is approximately 20℃, 'nori-hibi' is set in the sea near the mouth of a river.
(Nori-hibi is equipment to which the cultured nori adheres and grows. In the past, a tree-hibi or a bamboo-hibi was used. Today, a net-hibi is mainly used.)

The spores of nori adhere to nori-hibi, germinate and grow to be nori. The grown nori that is leafy is harvested in winter.

Nori around the world

Nori is cultured in China, South Korea, the UK and New Zealand, as well as in Japan. For a while it seems to have been cultured also in the USA.

The laver, a British variety, has been used as a food in South Wales, UK, since long ago. The food product 'en Laverbread,' which is a paste made by boiling laver, is eaten by spreading it over the bread as it is or frying it in oil. Laverbread is a kind of 'chinmi (delicacy)' in Japan, but in the north mountain region of Wales many people aren't familiar it, so it isn't a popular food there.

Though Japan is a big consuming area of nori and applies the import quota system, previously the import quota was allocated only to South Korea. However, because China applied for the import quota in 2003, South Korea, which feared the reduction of its import quota, asked for the liberalization of the nori market in Japan, but in 2004 South Korea finally filed a complaint with World Trade Organization (WTO) for breach of agreement. The import quota system of marine products in Japan did not exist in the other countries and there was a high possibility that the WTO's dispute-settlement panel would hand down a ruling that Japan was guilty. If Japan had lost the case on nori, the import quota system of other marine products would surely have been affected. Thus, Japan compromised by drastically increasing the import quota of nori for South Korea, and consequently South Korea withdrew its complaint in January 2006. The import quota of nori from South Korea will increase sequentially until 2015, becoming five times larger than that of 2004, and its market share will grow by seven-fold. However, because of the sushi boom worldwide and the increased domestic demand in South Korea, today the actual export to Japan is below the quota.

See 'Kankoku nori (Korean nori)' for information regarding nori in the Korean Peninsula.

In China, where cultivation began in around the 1990s, the main production areas are in the provinces of Jiangsu and Shandong. In China, nori is used for 'aji-tsuke nori,' snacks, 'onigiri' sold in convenience stores and so on, and the volumes of production and consumption are increasing. Though the import quota is applied for China, exports to Japan are very scarce because of the price and quality problem; however, Chinese nori is exported to destinations around the world (except for Japan) because of the influence of the Japanese food boom, as has occurred with sushi. Thus, exports to Japan which begun in 2005 have come to a virtual standstill today.

The nori production areas in Japan

The main production areas of nori are in Miyagi Prefecture, Chiba Prefecture, Aichi Prefecture, the coastal area along the Harima Sea of Hyogo Prefecture, the small islands in Kagawa Prefecture (Shodo-shima, Nao-shima and so on), Fukuoka Prefecture, Saga Prefecture and the coastal area along the Ariake Sea of Kumamoto Prefecture. Among them, the three prefectures along the Ariake Sea are the big production areas; they account for over 40% of the total production amount and produce large quantities of high-quality goods for gift-giving. Additionally, the coastal area along the Ariake Sea was where the problem of draining Isahaya Bay arose, when, just after the operation begun, the water contamination strongly influenced the production volume and quality of nori there, and in particular devastated the production area in Nagasaki Prefecture. Furthermore, the cultivation of nori is done in Okayama Prefecture, Hiroshima Prefecture, Tokushima Prefecture and so on in the regions of Chugoku and Shikoku.


Outside of Japan, there are many people who associate 'ita nori' with a sheet of carbon paper and detest it, saying that 'it sticks to the back sides of the teeth' or 'it's like eating a sheet of paper.'

For this reason, overseas the 'maki zushi (sushi roll)' has the rice part outside and the nori part inside.

The term 'nori' is used in the Romance language world just as it is. However, the 'laver' is not processed into 'ita nori,' and the word isn't a familiar one to people outside the UK.

The smooth side of nori is said to be a head and the other is to be a tail. When processed into 'ita nori,' the board side of nori becomes smooth, so in fact the heads and tails do not exist.

[Original Japanese]