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Dried aosa flakes in close-up on a white plate
  • Sea vegetable
  • あおさ

Aosa

What is in the bag when the label says aonori.

Flavor profile

Oceanocean 70%
Umamimild umami 55%
Grassgreenness 55%
Texturesilky 45%

The strengths are editorial judgments on a scale within the family, not measurements. They can be compared across the seaweed and kelp varieties, not directly against another family.

Aosa is the green seaweed most often found in the bag when the label says aonori. The blade is a single cell layer thick, which makes it softer and milder than the threaded aonori types, and it is used accordingly: a pinch in the miso soup, a handful in the tempura batter, or simmered down into tsukudani. It is also one of the most magnesium-rich foods in the Japanese nutrition tables.

Sensory analysis

Pyramid and character

Aroma

from the bag

  • mild seaweed
  • green notes
  • ocean

Taste

on the tongue

  • greenness
  • mild umami
  • ocean tone

Finish

what lingers

  • short
  • clean
  • fresh
UMAMISALINITYOCEAN TONEROASTFRESHNESSTEXTURESWEETNESS

Character 0-100 per axis, set relative to the other entries in the same family. An editorial judgment of a typical serving, not measurements.

Background

Facts

The name
あおさ in hiragana is the trade name for hitoegusa; アオサ as a biological name is the genus Ulva, an entirely different order, so whoever buys aosa rarely gets what researchers call aosa
Kinship
described in 1866 as Monostroma nitidum; Japanese farmed material was moved to Monostroma kuroshiense in 2015 and on to the genus Gayralia in 2022
Structure
the blade is one cell layer thick, while the Ulva species have two, and that is the entire difference in mouthfeel
Cultivation
farmed on nets in sheltered bays; Mie accounts for over 60 percent of Japanese production, with harvest from January to April
Amount
around 3,000 to 5,000 tons a year in fresh weight, which comes to 600 to 700 tons dried
Nutrition
dried aosa contains around 3,200 mg magnesium, 490 mg calcium and 5.3 mg iron per 100 g
Confusion
the cheap sprinkle aonori is in practice often aosa, since it costs a fraction of threaded suji-aonori
Use
miso soup, tsukudani, tempura and senbei; the aroma only opens up when hot broth hits the flakes

In the kitchen

Use

Dosage
a pinch per bowl of soup, sprinkled in at the last second
Temperature
added after the soup comes off the heat, never into boiling liquid
Note
it swells more than it looks like it will and turns silky in liquid; if it is to stay crisp it must not meet moisture until it is on the plate

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