Why do cooked seaweeds turn green?

Seaweeds, like any vegetable, can be prepared in a number of ways. They can be eaten raw, fried, baked, boiled, and dried. Each method changes the texture, taste, and in some cases, color.

If you haven’t seen the magic like color change of cooked seaweeds, watch the video below.

Here you see someone blanching kelp, where it turns from brown to bright green in seconds. This happens whenever a brown or red seaweed is heated, but why? As you probably remember from high school biology, plants get their green color from the light harvesting pigment chlorophyll. Seaweeds are no different, red, green, and brown seaweeds contain chlorophyll. However, brown and red seaweeds have additional pigments that give them a different colors; red seaweeds have phycoerythrin while brown seaweeds have fucoxanthin (image below).

It turns out that chlorophyll has a higher melting point (~150 C) than phycoerythrin and fucoxanthin. When Seaweeds are added to boiling water (100 C) the other pigments melt and dissolve leaving behind the bright green chlorophyll. This trick is used for the iconic seaweed salad (wakame). Just as in the video above, wakame starts out brown and is blanched to attain the attractive bright green color.

Seaweeds are one of the best things to eat to help preserve biodiversity and the planet

Last month, the United Nations released a report on biodiversity and ecosystems that found 1 million plant and animal species are currently facing extinction.

The World Wildlife Fund argues dietary monotony leads to a decline in biodiversity since many animals can’t thrive on land that has been transformed to farmlands. Did you know that 75% of the global food supply comes from just 12 plant and five animal species?

In response to this issue, the WWF published “Future 50 Foods,” a list of “foods we should eat more of because they are nutritious, have a lower impact on our planet than animal-based foods, can be affordable, accessible, and taste good.”

On this list there are two seaweed recommendations, wakame, and nori. While the authors clearly selected these on market availability, the same arguments can be made for a variety of seaweeds available by seaweed farms and local foragers.

Variety is the spice of life, but now it seems like it also might be what saves species diversity.

Seaweed common names: Laver

There are many names for commonly consumed seaweeds. However, the species they refer to vary by region and culture. We will cover some of the most commonly used names for seaweeds, and review the differences between connotation and denotation. This series will review some of the most common common-names in use.

Previous posts include: Nori, Wakame

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Laver

Laver, Latin for water plant, was adopted by the English some time in the 16th century. In Wales a popular dish was known as laverbread or bara lawr. To make laverbread, thin sheet like algae were collected from the rocky shores, boiled, pureed, then mixed with oats and fried. It was this popular dish that gave laver its current meaning: thin sheet like algae.

Today laver is liberally used to define edible seaweeds, but more specifically thin algae. Color adjectives became common to separate types of laver, green laver (Ulva sp.), purple laver (Pyropia sp. or Porphyra sp.).

Laver in the marketplace is considered a synonym of zicai (Chinese: 紫菜; pinyin: Zǐcài) in China, nori (海苔) in Japan, and gim (김) in Korea.

Seaweed common names: Wakame

There are many names for commonly consumed seaweeds. However, the species they refer to vary by region and culture. We will cover some of the most commonly used names for seaweeds, and review the differences between connotation and denotation. This series will review some of the most common common-names in use.

Previous posts include: Nori

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Wakame

Wakame is another edible seaweed popularized by the Japanese. You are probably familiar with wakame in the form of seaweed salad or as the little green strips within your miso soup.

ワカメ pronounced wakame, translates to seaweed, but in modern Japanese dictionaries directly refers to a specific species, Undaria pinnatifida.

Undaria pinnatifida is a brown seaweed (kelp) that grows substantially along rocky temperate coasts. The Latin root is Unda = wavy, and Pinna = pinnately cleft. Wakame in Japanese is derived from waka + me (若布, lit. young seaweed).

As early as the 8th century wakame was known to be harvested off the coast of Japan, China, and Korea. Undaria pinnatifida has since then spread to various regions of the world and has been added to the list of 100 most invasive species. Most recently Undaria pinnatifida crossed the pacific ocean again on debris carried from the 2011 tsunami.

Wakame is typically harvested, dried or blanched, and then sold. Upon purchase the wakame is then re-hydrated by soaking in water or soups.

While in the USA we are more familiar with the term wakame, other cultures call Undaria pinnatifida by other names: Qun dai cai (Chinese), Miyeouk (Korean), or sea mustard (English).

Today many foragers refer to other species as wakame. On the north coast some species of Alaria are being labeled as wakame as there is no native Undaria.