Nori

Nori(Japanese:海苔)is a driededible seaweedused in Japanese cuisine, usually made from species of thered algaegenusPyropia, includingP. yezoensisandP. tenera.It has a strong and distinctive flavor, and is generally made into flat sheets and used to wrap rolls ofsushioronigiri(rice balls).
The finished dried sheets are made by a shredding and rack-drying process that resemblespapermaking. They are sold in packs in grocery stores for culinary purposes. Since nori sheets easily absorb water from the air and degrade, adesiccantis needed when storing nori for any significant time.
Nori—despite not being cultivated by humans until the 1600s—has been popular since the pre-modern era in Japan, having been used as currency, offerings at shrines, and food since the 700s.
Originally, the termnoriwas generic and referred toseaweeds, includinghijiki.One of the earliest descriptions of nori is dated to around the eighth century. In theTaihō Codeof 701 CE,noriwas already included in the form of taxation.Local people were described as drying nori in theHitachi ProvinceFudoki(721–721 CE), and harvesting of nori was mentioned in theIzumo ProvinceFudoki(713–733 CE).In theUtsubo Monogatari, written around 987 CE,noriwas recognized as a common food.
Nori had been consumed as paste form until the sheet form (ita-nori板海苔) was invented inAsakusa,Tokyo, around 1750 in theEdo periodthrough the method ofJapanese paper-making.
The word "nori" first appeared in an English-language publication inC. P. Thunberg's Trav., published in 1796.It was used in conjugation as "Awa nori", probably referring to what now is called "aonori", i.e.,green laver.
When Japan was in need of high food production afterWorld War II, production of nori was in decline. They sought to cultivate nori in addition to traditional wild harvesting from the sea. Due to a lack of understanding of nori's three-stage life cycle, however, those attempting to produce nori artificially did not understand why their cultivation methods were not being productive with nori. The industry was rescued by knowledge derived from the work of BritishphycologistKathleen Mary Drew-Baker, who had been researching the organismPorphyria umbilicalisthat grew in the seas around Wales and was harvested for food (laverbread), as in Japan. Her work was discovered by Japanese scientists who applied it to artificial methods of seeding and growing the nori, rescuing the industry. Kathleen Baker was hailed in Japan as the "Mother of the Sea" and a statue was erected in her memory.She is still revered as the savior of the Japanese nori industry.
The wordnoristarted to be used widely in the United States and the product (imported in dry form from Japan) became widely available at natural food stores and Asian-American grocery stores in the 1960s due to the macrobiotic movementand in the 1970s with the increase of sushi bars and Japanese restaurants.
In the 21st century, the Japanese nori industry faces a new decline due to increased competition from seaweed producers in China and Korea, and an increase in domestic sales tax.
Production and processing ofnoriis an advanced form of agriculture. The biology ofPyropia, although complicated, now is well understood, and this knowledge is used to control the production process. Farming takes place in the sea where thePyropiaplants grow attached to nets suspended at the sea surface and where the farmers operate from boats. The plants grow rapidly, requiring approximately 45 days from "seeding" until the first harvest. Multiple harvests can be taken from a single seeding, typically at approximately ten-day intervals. Harvesting is accomplished using mechanical harvesters of a variety of configurations. Processing of raw product is mostly accomplished by highly automated machines that accurately duplicate traditional manual processing steps, but with much improved efficiency and consistency. The final product is a paper-thin, black, dried sheet of approximately 18 cm × 20 cm (7 in × 8 in) and 3 grams (0.11 oz) in weight.
Several grades of nori are available in the United States.  The most common (and least expensive) grades are imported from China, costing approximately six cents per sheet.  At the high end, ranging up to 90 cents per sheet, are "delicateshin-nori" (norifrom the first of the year's several harvests) cultivated in theAriake Sea, off the island of Kyushu in Japan.
In Japan, more than 600 square kilometres (230 sq mi) of coastal waters are given to producing 350,000 tonnes (340,000 long tons) of nori, worth more than a billion dollars. China produces approximately a third of this amount.
Wild seaweed is still gathered to make nori, often found growing on rocks at the beach. Such wild nori is callediwanori("rock nori"), and are known for their rougher texture and taste.
Nori is commonly used as a wrap forsushiandonigiri(rice balls). The dry seaweed is used to pick up rice balls without getting the hands sticky.Senbei(rice crackers) sometimes contain a piece of nori as well.
Strips or small sheets of nori are used as garnish for noodles, soups, and rice dishes. Flakes of nori are used infurikakeseasonings, to be sprinkled over rice or added toonigiri. Very small flakes or powdered nori can be dusted over a variety of savory foods.
Typically, nori is toasted prior to consumption. Toasted nori is calledyaki-nori. A common secondary product is toasted and flavored nori (ajitsuke-nori), in which a flavoring mixture (variable, but typicallysoy sauce, sugar,sake,mirin, and seasonings) is applied in combination with the toasting process.Nori is also eaten by making it into a soy sauce-flavored paste,nori notsukudani(海苔の佃煮). Sometimes it is also used as a form offood decoration, such as creating faces oranimecharacters inbentoboxes.
A related product, prepared from the unrelatedgreen algaeMonostromaandEnteromorpha, is calledaonori(青海苔literallyblue/greennori) and it is used as anherbon everyday meals, such asokonomiyakiandyakisoba.
Raw seaweed is 85% water, 6%protein, 5%carbohydrates, and has negligiblefat. In a 100 gram reference amount, seaweed is a rich source (20% or more of theDaily Value, DV) ofvitamin A,vitamin C,riboflavin, andfolate. Seaweed is a moderate source (less than 20% DV) ofniacin,iron, andzinc. Seaweed has a high content ofiodine, providing a substantial amount in just one gram.A 2014 study reported that dried purple laver ("nori") containsvitamin B12in sufficient quantities to meet theRDArequirement (Vitamin B12 content: 77.6 μg /100 g dry weight).By contrast, however, a 2017 review concluded that vitamin B12 may be destroyed duringmetabolismor is converted into inactive B12analogsduring drying and storage.TheAcademy of Nutrition and Dieteticsstated in 2016 that nori is not an adequate source ofvitamin B12for humans.
Nori may contain toxic metals (arsenicandcadmium), whose levels are highly variable among nori products. It also containsamphipodallergens that may cause serious allergic reactions, especially in highly sensitized crustacean-allergic people.
Thered algaegenera is also consumed inKorean cuisineasgim, inChinese cuisineashaitai(海苔) orzicai(紫菜), and inWalesandIrelandaslaverbread.