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Hijiki

Hijiki is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Hijiki rather than just read about it. In short: Hijiki (ヒジキ, 鹿尾菜 or 羊栖菜, hijiki) (Sargassum fusiforme, syn. Hizikia fusiformis), sometimes called hiziki or tot (Korean: 톳), is a brown seaweed that grows wild on the rocky coastlines of East Asia.

Hijiki — main illustration
Hijiki — illustration

Key takeaways

  • Hijiki belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Hijiki to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Hijiki from memory before moving on to harder problems.

Reference excerpt

Hijiki (ヒジキ, 鹿尾菜 or 羊栖菜, hijiki) (Sargassum fusiforme, syn. Hizikia fusiformis), sometimes called hiziki or tot (Korean: 톳), is a brown seaweed that grows wild on the rocky coastlines of East Asia. Hijiki has been a part of the Japanese culinary sphere and diet for centuries. Hijiki has been sold in United Kingdom natural products stores for 30 years and its culinary uses have been adopted in North America. Recent studies have shown that hijiki contains potentially toxic quantities of inorganic arsenic, and the food safety agencies of several countries (excluding Japan), including Canada, the United Kingdom, and the United States, have advised against its consumption.

In the West In 1867 the word "hijiki" first appeared in an English-language publication: A Japanese and English Dictionary by James C. Hepburn. Starting in the 1960s, the word "hijiki" started to be used widely in the United States, and the product (imported in dried form from Japan) became widely available at natural food stores and Asian-American grocery stores, due to the influence of the macrobiotic movement, and in the 1970s with the growing number of Japanese restaurants.

Appearance and preparation Hijiki is green to brown in colour when found in the wild. Fishermen and professional divers harvest the hijiki with a sickle at low tide during the spring tide from May to March. After collection, the seaweed is boiled and dried before being sold as dried hijiki. Once processed, dried hijiki turns black. To prepare dried hijiki for cooking, it is first soaked in water then cooked with ingredients like soy sauce and sugar to make a dish that goes by the same name. In Japan, hijiki is normally eaten with other foods such as vegetables or fish. It may be added to foods that have been steamed, boiled, marinated in soy sauce or fish sauce, cooked in oil, or added to soup, stir fries or quiches. Hijiki may be mixed with rice, but not used as a wrap, to prepare sushi. Konjac is typically prepared with hijiki mixed in to give the dish known by the same name its characteristic grey color and texture. In Korea, the seaweed is called tot (톳) and eaten as namul (seasoned vegetable side dish) or cooked with bap (rice).

Arsenic health risk

Several government food safety agencies advise consumers to avoid consumption of hijiki seaweed. Testing showed that it contains significantly higher concentrations of inorganic arsenic than other types of seaweed, and these results have been independently verified. Government food safety agencies that advise against consumption include the Canadian Food Inspection Agency (CFIA), the Food Standards Agency (FSA) of the United Kingdom, and the United States Department of Agriculture (USDA). The Ministry of Health, Labour and Welfare of Japan responded with a report pointing out that while the consumption of more than 4.7 g hijiki seaweed per day could result in an intake of inorganic arsenic that exceeds the tolerable daily intake for this substance, the average daily consumption for Japanese people is estimated at 0.9 g. Several of the reports from other food safety agencies acknowledged that occasional hijiki consumption was unlikely to cause significant health risks but advised against all consumption regardless. There are methods to process and greatly reduce arsenic from hijiki. Although no known illnesses have been associated with consuming hijiki seaweed to date, inorganic arsenic has been identified as carcinogenic to humans. Exposure to inorganic arsenic has been linked with gastrointestinal effects, anemia, and liver damage. People who follow a macrobiotic diet that often includes large amounts of seaweed may be at greater risk.

See also Arsenic poisoning

References

Further reading Zou, Hui-xi; Pang, Qiu-Ying; Zhang, Ai-Qin (January 2015). "Excess copper induced proteomic changes in the marine brown algae Sargassum fusiforme". Ecotoxicology and Environmental Safety. 111: 271–280. Bibcode:2015EcoES.111..271Z. doi:10.1016/j.ecoenv.2014.10.028. PMID 25450944.

External links Canadian Food Inspection Agency — Factsheet Food and Environmental Hygiene Department of Hong Kong — Hijiki and Arsenic Food Standards Agency of the United Kingdom — Hijiki: your questions answered New Zealand Food Safety Authority — Hijiki media release Seaweeds Used as Human Food

Illustrations

Hijiki illustration
Hijiki illustration
Hijiki illustration
Hijiki illustration
Hijiki illustration

Worked examples

Example 1 — a first encounter with Hijiki

Start with the simplest possible case. Write down what Hijiki claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Hijiki before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Hijiki ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Hijiki

In research
Hijiki appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Hijiki in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Hijiki is common in secondary-school and first-year university syllabi. It links to neighbouring topics Ark of Taste foods, Edible seaweeds, Fucales, so understanding it makes those chapters shorter.
In everyday life
Look for Hijiki outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Hijiki in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Hijiki means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Hijiki out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Hijiki in simple terms?

Hijiki (ヒジキ, 鹿尾菜 or 羊栖菜, hijiki) (Sargassum fusiforme, syn. Hizikia fusiformis), sometimes called hiziki or tot (Korean: 톳), is a brown seaweed that grows wild on the rocky coastlines of East Asia.

Why does Hijiki matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Hijiki?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Hijiki.

Tags

  • Ark of Taste foods
  • Edible seaweeds
  • Fucales
  • Japanese condiments
  • Japanese cuisine terms
  • Japanese vegetables
  • Korean condiments
  • Protists described in 1931

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