Nori and Karengo, What is The Difference ?

Karengo, NZ's nori growing on the rocks, photo by Kim Westerskov

For many of us, sushi has been our first contact with seaweed as a food. Because of the current influence of Asian Cuisine and the well deserved superfood status seaweed is enjoying,  it has  become increasingly popular. Although seaweed has been part of the traditional diet of many coastal communities around the world, it is best known as ‘an Asian food’ because it is such a big part of their everyday meal (15-20%). But when one tries to find out more about seaweed, it can be a bit confusing at first. Not only are there many different seaweed species, but the name sometimes changes according to the country of origin. And then there is the whole business of knowing what to do with it… This post is about de-mystifying nori… Nori is the Japanese word that refers to a group of red seaweed traditionally classified as ‘Porphyra‘ *. There are many different types of porphyra around the world (over 100 different species) and although the word ‘nori’ is the most popular/universal name for this type of seaweed, it is also known as sleabhac, laver, sladai…to name only a few. In New Zealand, Nori is called Karengo or Parengo and to date, NIWA scientists have identified about 35 species*growing along our coasts. Colour, texture and shape may vary according to the individual specie. Their blades (the equivalent of leaves on land plants) can be pink, purple, gold, or greenish and range from huge sheets with the texture of cellophane to long, irregular ribbons. Some are really tough and others are very delicate and tender, but all are just one cell thick – making them unique among seaweeds. Karengo grows in the inter-tidal area of the seashore, mostly anchored to rocks; at low tide, the plant is exposed to air and the elements for a number of hours every day and then under water at high tide. Research by NIWA on two karengo species at Kaikoura shows that the blades are able to re-grow from the base after harvesting. For much of the year Karengo cannot be seen easily, it may be only a speck on the rocks. Like other plants, their main growing period is spring. At maturity and from a distance, it may look like a torn black plastic bag melted on the rock.

Visual representation of various species of NZ Karengo, courtesy of Dr Wendy Nelson, NIWA

* To complicate matters, scientists are now discovering that some of the species called porphyra are actually something else (Clymene, Lysithea and Pyropia – most NZ species are Pyropia as are the commercial species in Asia). The fact remains that they are quite similar when it comes to the palate. In New Zealand, Karengo is considered taonga by Māori and can be gathered from the wild for personal use. There is only one licence to harvest Karengo commercially in New Zealand. Harvest is made between July and September along a defined stretch of coast in the South Island; the two species growing there are tissue-like ribbons with delicate purple hues. Karengo harvest is done manually, equipment is not permitted . The amount allowed to be harvested is pre-determined and very limited. New Zealand Karengo/nori goes through very little processing and therefore retains all of its natural nutrition. It is harvested during the winter when it reaches maturity and rinsed in sea water to wash out any sand or debris on its surface. It is then naturally air dried and packed in sacks to be shipped to Pacific Harvest’s facility near Auckland. There, it is milled and cleaned. Any debris that will have remained in the curly leaves is removed manually, then it is graded to various sizes and packed. The cleaning is a lengthy process that is necessary to achieve a quality product. The nutritional profile of Karengo includes relatively high concentrations of protein, calcium, iron, fiber, potassium, magnesium, phosphorous, iodine and vitamins A, B1, B2, C, D, and E. It also contains taurine (which is documented to lower blood cholesterol), no fat and is a good source of Omega-3 fatty acids. It has natural anti-inflammatory, anti-biotic, anti-fungal, antiviral & anti-parasitic effects. Studies are being done on its ability to cure stomach cancer and ulcers.   In Asia, virtually all nori is processed into sheets/wraps. The production and consumption of nori in the form of dried or roasted sheets dates back 1,300 years. Nori utilization was first recorded in Japan’s first book of laws in 701 A.D., as a taxable agricultural product. Originally, Nori was harvested from the wild but as demand surged, cultivation started. According to Wikipedia, seaweed farming began in Japan as early as 1670. In Japan alone  the annual production value of Nori amounts to US$2 billion and is one of the world’s most valuable crops produced by aquaculture. Now all the nori coming from Asia is cultivated. In the 1960s, important  scientific breakthroughs took place in nori cultivation, (artificial seeding, new concepts in growing structures, mechanization of processing and adaptation of fast-growing varieties of Porphyra) and annual yield of nori have increased rapidly in Japan, Korea and China. China is currently (2004) the largest producer of nori, followed by Japan and the Republic of Korea. Nori cultivation is the largest sub-industry in Japanese aquafarming, employing 16,800 workers. (FAO).

Nori ‘breeding’ in lab pools


net structure used in Asia


seeding the nets

In much of Asia, nori cultivation is well understood and very productive. First the spores are bred and multiplied in lab pools where temperature and light are optimised. Nets are then seeded with the spores and suspended in clean ocean water. As the spores are nourished by nutrients in the water and the sunlight of summer and fall, they grow into increasingly large strands of seaweed. In this system, also known as the “pole system”, the nori nets are hung between poles. At low tides, the nets are exposed to air and become dry. Techniques of floating nets now allow nori cultivation in deeper areas of the sea.

Tying nets to the structure

nori nets under water at high tide

nets exposed at low tide

After rearing in the open sea for 40 or 50 days (may vary according to species), the first harvesting phase begins. Harvesting activities can last for 5 months. The interval of harvesting is every 10-15 days; therefore, the crop is harvested 10-12 times annually.  The Nori strands are cut from the net and then washed and ground into slurry. The slurry is then fed into a machine which flattens and dries the seaweed into uniform sheets, much like the process of making paper. The Nori sheets are then roasted and graded. Most nori sheets are also glazed, giving them their shiny surface and salty taste. The glaze can give the sheet a variety of flavours but also serves the purpose of keeping it together; like in sea salt the abundance of minerals in seaweed attracts moisture which may make the wrap more fragile to breaking apart.

collecting nori in purpose-made boats

processing nori into sheets

glazed nori sheets

(pictures from a variety of Japanese sites and Although nori farming is the subject of experimentation in other parts of the world (namely the USA and UK), they are not likely to become major producers. In Asia, a large amount of biotechnology work has taken place for decades to hybridise, cross and mutate various indigenous species to improve growth rate, increase resistance to disease and prolong cultivation period. As a result, the knowledge base and farming experience is staggering there and when added to the size of their domestic demand and lower living costs, the reality is that Asia  has a production capability that is very challenging to compete with.

Martin harvesting karengo

Karengo is not prepared into sheets/wraps for several reasons. The harvest is very limited and further treatment would make the seaweed un-affordable. Equally important, NZ’s karengo tradition does not use wraps and in this way is more akin to the European ways of using laver. Click the link to read more about Karengo. Karengo has very unique culinary qualities: one of them is that it changes its taste with the way it is used. Soft dried straight out of the bag, it has a flavour akin to dried mushrooms or smoked tea. In that form it is lovely with eggs, potatoes or as a simple snack. When dried further into a crisp the flavour is intensified and nutty, it is delicious with nuts & seeds or as a garnish. When moist, the taste is that of mild anchovies and is a great alternative to the fish in Mediterranean dishes. Pacific Harvest also uses Karengo to make seaweed seasonings (Furikake) and chutneys. Be sure to look up some of the Karengo recipes on this blog 🙂 and click the link for more recipes . Also, check Broad Leaf Karengo Recipe Brochure and Karengo Recipe Brochure

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