"Nori" is A Precious Present from MOTHER SEA
Basic size of Nori sheet is 19cm x 21 cm, which is the conversion of old Japanese measurement: 6.3 Sun x 7 Sun. (1 Sun = 3.03 cm)
Full-sheet, a half, one-third, one-f ourth, one-sixth, one-eighth, and one-twelfth are popular sizes.
A half and one-fourth sizes are for hand-rolled sushi. One-third size is for regular “Onigiri”, and one-fifth is for small size “Onigiri”. Nori served with breakfast is usually one-eighth or one-twelfth size.
Color components in Nori can be divided into three categories: chlorophyll, phycoerythrin and phycocyanin. Another is carotenoid.
When Nori is heated, the majority parts of blue and red color components are decomposed, so that heat-resistant chlorophyll (green) becomes visible. (As the time goes by, it turns to slightly brown-green due to denature of the remaining blue and red color components.)
In case that the toasted Nori is moistened, it turns to purple with the blue and red color components due to decomposing of green component which is weak against moisture.
The three basic tastes in Japanese food are glutamic acid (contained in Kombu), inosinic acid (contained in dried bonito) and guanylic acid (contained in mushroom soup).
A natural food containing all of them is only Nori, but not any others do.
It is quite reasonable for the good taste that Nori is taken together with rice.
Alcohol is de-toxified in human liver by decomposing it. At that time some amount of protein is consumed, and Nori contain a lot of the protein. It can be said, therefore, that Nori is a good friend of alcoholic drink.
Generally, the smooth side is called “right side”, and the rough side is “reverse side”. It is recommended to wrap a rice ball or a hand-rolled sushi with the rough side contacted to the rice. The external looks better and provides a good feel to your mouth.
Nori should be kept in an air-tight bag or container together with desiccant. And it is still better to keep it in a refrigerator.
After taking out of the refrigerator, wait to open the package till its temperature has become nearly the room temperature.
In 1966, “February 6” was determined as “Nori Day”, by the Nationwide Japanese Nori Farmers.
The first written record about Nori was appeared in “Taiho Code” of 701 as a report of taxation. The established date, the January 1 of Taiho (the name of the Japanese era), was the 6th day of February in the solar calendar now we are using. For greater future development, it was settled as the starting point of the Japanese Nori world.
To present fresh Nori to Ieyasu, the Nori farming was started in the seashores around Shinagawa and Omori on Tokyo Bay. The shogunate made almost all of them a source of government income. With the farming progressed, Nori became one of the Edo specialties, and popular among the people.
In the old days in Japan, when somebody got burned, the affected part was immediately cooled with water, and wetted Nori was put on it for cooling and protection. A light burn was with a single sheet of Nori, and a worse was with two or three sheets. It was an old-time first-aid.