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FAQ about Seaweed

Frequently asked question about seaweed presented by
Japanese seaweed manufacture, "Kurakon Food Corporation".

about General Seaweed

What is seaweed?
Seaweed is the collective term for algae grown in sea water.
There are two types of water grown plants, which are algae and seed plants, and the one that is grown in sea water is seaweed.
For more detail, click here → What is seaweed?
What kinds of edible seaweed are there?
There are many kinds of edible seaweeds. Typical seaweeds include Kombu seaweed, "the king of seaweed", wakame, hijiki, nori, arame, and dulse. They all are biologically different species.
For more detail, click here → Uses of Different Seaweed
Are there any minerals in seaweed? If so, what kinds of minerals are in it?
Seaweeds are filled with various minerals. Generally, seaweeds are filled with minerals but each mineral has different minerals. For each nutrient, click link below.
Are all the seaweeds edible? Are there non edible seaweeds out there?
There are toxic seaweeds out there. For example, Gracilaria, a type of red algae, may cause food poisoning if no proper handling were performed. Please do not forage seaweed without skill.
Are there any uses other than edible use to seaweed?
There are various non edible uses to seaweed. From Kimono, a Japanese traditional costume, to fire extinguisher, seaweeds are used everywhere.
  • Before coloring kimono textile, seaweed called glue plant and gojiru, soup made from grinded soybean, is mixed together and spread on a texture to avoid uneven coloring.
  • For fire extinguisher using bubble, ingredients called carageenan extracted from seaweed are used. By adding this, bubbles will have more durability.
  • For cosmetics, carageenan is used to add thickness. For same reason, carageenan is used for toothpaste, shampoo and such.
There maybe product using seaweed around you not noticing it!
Where can you buy seaweed?
Organic supermarket and Asian supermarket. Seaweeds can be found in organic supermarket and Asian supermarket. It is usually located on grocery section. Sometime, seaweed salad can be found at deli section.
How to store seaweed?
Avoid humid, high temperature and direct sunlight. Long term storage is possible if it is completely dried. When store under direct sunlight, change in color may occur.
Why is wet seaweed so slimy?
Because seaweed are rich in alginate. Brown algae are rich in alginate and soluble fiber and these elements get slimy when they are wet. These two nutrients are especially rich in Kombu seaweed and is said that wet Kombu was used to transport heavy rock by sliding on top by using this trait.
Is seaweed good for hair?
Unfortunately, there is no scientific evidence. Seaweed is said to help grow healthy black hair but there is no scientific evidence to proof that this is true. Main component of hair is protein and Kombu barely have protein in it. However, Kombu is rich in iodine. Iodine is said to boost metabolism and stimulate growth hormone so there might be some connection to healthy hair.

about Kombu

What is Kombu seaweed?
Kombu seaweed is specie of seaweed and the only specie that can be used for dashi broth (soup broth). Kombu seaweed is one of edible seaweed and Umami, fifth taste, was found from Kombu.
For more detail, click here → Japanese Cuisine, Kombu Seaweed, and Umami
Since Kombu seaweed is rich in Umami, it is the only seaweed that is used for dashi broth. Thus, called King of seaweed.
For more detail, click here → Uses of Different Seaweed
What is Dashi broth?
Liquid that is rich in Umami and used for soup.
Usually used in Japanese cuisine. It is a building block of Japanese cuisine and there are two type of Dashi. Dashi made solely from Kombu seaweed, and dashi made with Kombu seaweed and bonito flakes. 
For more detail, click here → How to Make Dashi broth
How to use Kombu seaweed?
From simmering dish to stir-fry, Kombu seaweed can be used in many ways! For more recipes click here → Kombu seaweed recipes
What kinds of nutrients are in Kombu seaweed?
Kombu seaweed has various minerals including potassium and fiber. Click here for more detail → Kombu Seaweed Nutrition Aspects
What is the difference between Kombu seaweed and kelp?
It is not definite, but Kombu can be thought like a kind of kelp. First of all, word Kombu derived from Japanese word.Japanese dictionary states that it is collective term for seaweed that belongs to laminaria genus. According to English dictionary, it is seaweed that belongs to laminaria family including laminaria genus and macrocystis genus (such as giant kelp). Thus, Kelp covers kombu and can conclude that Kombu is part of the kelp.
What is the white grain on surface of Kombu seaweed?
It is a block of Kombu nutrients. White grain on surface of Kombu seaweed is minerals from kombu seaweed crystallizing when sun dried. They are nutrients derived from Kombu and have no harm to the body and quality of product.
What is the white powder on surface of Kombu seaweed?
It is umami condensing on surface of Kombu seaweed. A white powder on surface of Kombu seaweed is Umami called Mannit. They are nutrients derived from Kombu and have no harm to the body and quality of product. Please wipe it off with tightly wrung cloth.
Dashi broth turned into blue when I added Kombu seaweed! It usually turns lightly yellow color... why?
It is due to iodine starch reaction. When different color of dashi comes out, you would be scared. But not to worry, this blue dashi broth is due to iodine starch reaction. Kombu seaweed consist iodine. When there is starch food, like rice, flour, potato on your hand or pot, using chlorine filled water, dashi broth may turn blue or bluish purple. It does not affect flavor or quality of product. When blue dashi is heated, color will disappear.
Dashi broth is prepared by putting Kombu seaweed in water or hot water. How come dashi won't come out from Kombu seaweed in ocean?
It is due to selective permeability. Cell membrane in the Kombu seaweed has an ability to absorb necessary nutrients and discharge unnecessary waste. This function is basic to the entire living organism. Glutamic acid, a reason of umami rich Kombu, is necessary component for Kombu to grow. Thus, while Kombu is still alive, selective permeability avoid glutamic acid to run off.
What is the relationship between kombu seaweed and kombucha?
It is two completely different things. Kombu seaweed is specie of seaweed and Kombucha is fermented tea beverage made of microbes originated from Mongolia. Actually, there is Japanese beverage that has same exact pronunciation "Kombucha" meaning Kombu tea but it is said that this Japanese tea and fermented tea's name got mixed up somehow. Some claims that the reason of this mix up is due to the look of what is left from fermentation process looked like seaweed but we do not know if this is true or not.
Is Kombu seaweed edible by itself? Is heating necessary?
It can be eaten raw. In Japan, where Kombu seaweed is consumed almost everyday, some people eat it raw just like snack. Though, Kombu seaweed is sun dried on the beach and may have sands on it so please wipe off surface with tightly wrung cloth before consuming.
Is there any way to use for used kombu seaweed?
It can be used various ways. There still are lots of nutrients and minerals are left in Kombu seaweed. Keep it in freezer, and when there is enough amounts, it can be used for soup filling, salad topping by mincing it.

about Wakame

What is wakame?
Specie of seaweed and has crispy texture. Mainly used for soup and salad.
For more detail, click here → Uses of Different Seaweed
What kinds of nutrients are in wakame?
Wakame has various minerals including calcium and fiber. Click here for more detail → Wakame Nutrition
How to use wakame?
Here is recipe of miso soup using wakame.Click here → Uses of wakame
Is wakame edible without putting on a heat?
Wakame is edible without putting on a heat if wakame is packaged at sanitary location.In Japan where wakame is consumed daily, wakame is cooked by boiling water during production process. Our wakame is also edible without any cooking. For wakame that is processed outside of Japan, please contact manufacture.
There is fuzzy hair on wakame! What is this?
It is a part of wakame and is edible.In Japan where wakame is consumed daily, it is called "mousou" in Japanese but what it's for and why it's there is not known. Only known fact is that it is safe to consume.
Is wakame originally this brilliant green?
Wakame is originally brown color.Wakame's pigment is made up from fucoxanthin and chlorophyll. During manufacture process, wakame is boiled and only fucoxanthin's brown color will be lost. Green color from chlorophyll will still be there, causing wakame to be brilliant green.
What is the tip for cooking wakame?
Avoid overcooking.When wakame is overcooked, wakame will dissolve, loosing its crispiness. When using wakame for miso soup, add wakame at last.

about Hijiki

What is Hijiki?
Specie of seaweed and is rich in iron.Mainly used for simmering dishes. For more detail, click here → Uses of Different Seaweed
What kind of nutrients are in Hijiki other than iron?
Hijiki has various nutrients other than iron such as calcium.For more detail, click here →Hijiki Nutrition
How to use Hijiki?
Here is the recipe for Stir-fried hijiki.Click here for detail → Uses of Hijiki
Is Hijiki edible without putting on a heat?
Heating is not necessary for hijiki but please soak in water for reconstitution.Usually, hijiki produced in Japan has gone through heating process in production and has no need to put on heat at your home. For production process, click here → Production process of Hijiki
Though it is safe to eat uncooked hijiki, it does not taste well, so we recommend rehydrating before consuming. For hijiki processed outside of Japan, please contact manufacture.
What is the tip for cooking Hijiki?
There are 2 advices.Food that pairs well with hijiki.
  • Pairing with oil → Not just only for simmering dish, it can be enjoyed in stir-fry, fried dishes.
  • Vitamin D rich food → Will help absorb calcium of hijiki.
  • Protein or Vitamin C rich food → Will help absorb iron of hijiki.
About preparation.
When in a hurry, use hot water to rehydrate hijiki. However, make sure hot water is below 50°C. When the temperature is too high, nutrients from hijiki will run off.
Why is Hijiki black colored?
Some says it is because the tannin gets oxidized.Actual hijiki that growing in ocean is brown color. Hijiki is rich in tannin which causes astringent flavor and can not be eaten without processing them. As this page states, hijiki is simmered for long time. By doing so, cell break down occurs and most of the tannin run off and become edible. Tannin that did not run off at this process oxidizes in hijiki, causing hijiki to turn black.
General SeaweedKombuWakameHijiki
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