Introduction: weeds and wracks
A few years ago when I did some research for a book on edible seaweeds (Mouritsen 2013), I had the chance to visit the mighty herbarium for the large marine algae on the top floor of the Natural History Museum in South Kensington in London. The then curator Jenny Bryant was so kind to open the precious collections in the socalled Cryptogamic Herbarium for me. Among the 600,000 seaweeds specimens from all over the world—some of them collected at famous expeditions—I found, e.g., specimens of Porphyra (Fig. 1) from the private collection the famous Kathleen Mary Drew-Baker, the phycologist who solved the puzzle of the live cycle of Porphyra, thereby laying the scientific foundation for rational farming af Porphyra for nori production.
What I also found was a pretty, little, folded book with fifteen pages, each mounted with a different seaweed species, probably collected as a hobby by a girl on one of the English Channel Islands at the beginning of the 19th Century (Fig. 2).
In the first half of the 19th Century, English laymen developed a growing interest in, and infatuation with natural history, leading them to devote their leisure time to the study of Nature, often by the seashore (Boalch 2006). Not long before, the Swedish naturalist Carl von Linné had introduced a classification system, but many species had not yet been designated by unique Latin names and were known by names that varied from one district to another. English ladies, in particular, enjoyed gathering up strange objects on the beach (Fig. 3). Often led by the local curate or doctor, they went along the shore at low tide collecting bits of seaweed, which they dried, pressed carefully, and mounted on paper. These specimens were labeled with fanciful names such as mermaid’s shaving brush, sea- girdles, peacock’s tail, and sea lace.
The interest in seaweeds seems also to have inspired poets to point out the injustice inherent in referring to seaweeds as weeds. On the back cover of the little folded book, mentioned above (Fig. 2), the girl had copied a poem of an unknown poet Curtis. It reads like this:
Algae, bright order!
By Cryp-to-gamists defended – Translate marine plants
as Linnaeus intended.
You collect and admire us,
we amuse leisure hours; “Then call us not weeds,
we are Ocean’s gay flowers.”
In the poem, the seaweeds speak to directly us: “do not call us weeds!”
But not only suffering the humiliation of being called weeds—seaweeds have yet another burden to bear. Their often off-putting and smelling appearance, lying as rotten castaways on the foreshore, have given way to ill-famed names like ‘wracks.’
This unfortunate naming goes back to the 16th Century and to a Dr. William Turner (1508–1568) who is considered the ‘father of English botany.’ He is responsible for the linguistic association between seaweeds and plants. When he compiled the first scientific treatise on plants giving them English names in the 16th Century, he regarded seaweeds as useful herbs and included them in his treatise, using the term ‘seawrake’. This was an allusion to their origin, like shipwrecks, as something that washed up from the sea.
The somewhat condescending description of seaweeds in Europe goes way back. “Nihil vilior alga—there is nothing more worthless than seaweed” is a quote attributed to the Roman poet Virgil (70–19 BCE). One can almost imagine Virgil walking along the Mediterranean Coast pinching his nose.
In the Far East seaweeds enjoys a much higher reputation, esteem, and even deep respect. “Seaweed is a delicacy, fit for the most honored guests, even for the king himself” writes Sze Teu 600 BCE. Seaweeds have for millennia been an important and valued source of food in Far-East Asia and in the Pacific.
Today some seaweed lovers prefer to call seaweeds for sea greens or sea vegetables.
Nutritious and healthy, but taste comes first
I would like to use this background to set the scene for the evening’s dinner talk about the taste of seaweeds. We are after all just in the process of enjoying a meal.
Taste comes first. No matter how nutritious and healthy a particular kind of foodstuff is, no one is going to consume it for long if it is not tasty. This is particular important to keep in mind when introducing seaweeds into the Western cuisine.
There is indeed much to say in favor of seaweeds as a healthy and nutritious food source (Holdt and Kraan 2011; Pomin 2012; Mouritsen 2013; Cornish et al. 2015). Although seaweeds can only be a minor part of a daily diet, they are in many ways optimal for hu- man nutrition because they contain a bounty of important minerals, trace elements, vita- mins, proteins, iodine, poly-unsaturated fatty acids, and plenty of both soluble and insoluble dietary fiber with few calories.
But seaweeds also have a large and unexploited potential for gastronomical innovation with focus on flavor profile and mouthfeel. They can find use in practically any kind of dish in the daily kitchen as well as in high cuisine. All this is well known in China, Japan, Hawaii, Korea, and other countries where there is a long tradition for using seaweeds in the national and local cuisines. This is now also becoming known in the Western world, not least promoted by innovative chefs and the health-food movement.
But are these weeds actually tasty? And are they tasty for your palate? If you, e.g., ask people in Japan, they will say: “of course they are tasty!”
Before we proceed, let us define what taste is. Here it is getting a little difficult because different languages have different words and vocabularies for taste, and the different taste impressions are not coded in different languages in the same way. Some languages, e.g. Danish, does not even have a term for flavor, and we are in the West only getting accustomed to using taste expressions like umami and kokumi.
We use all our five primary senses when we have a taste experience. This is also true when tasting seaweeds. And seaweeds do have something to contribute to all five senses. We see, we feel, we hear, we taste, and we smell seaweeds. When adding to this that a taste experience is intimately dependent on tradition, culture, social environment, and previous experiences, it is getting pretty complicated but also exciting.
Before I talk about the actual taste of some seaweeds, let me point to two features of seaweeds that are highly appreciated, e.g., in Japan: first, seaweeds can be beautiful and aesthetically pleasing to the eye and, second, they impart a rich variety of mouthfeel (Mouritsen and Styrbæk 2017). In the Far East, an aspect of the taste experience which we hardly have a word for, mouthfeel, is possibly the most appreciated—that is, the way the foodstuff feels in the mouth. Did you know that the Japanese language have 408 expressions to describe how food feels in the mouth, on the tongue, at the palate, between the teeth, and so forth? In the USA it is only 78 words (Drake 1989).
Seaweeds can for example be tender, tough, soft, firm, hard, gummy, crunchy, slimy, crisp, chewy, dry, wet, plastic, elastic, slippery, etc.
Umami: the fifth basic taste from seaweeds
But back to taste: can seaweeds be taste and delicious? Well—why not? After all one of the five basic tastes, umami (in addition to the four classical tastes: sour, sweet, bitter, and salty) (Mouritsen and Styrbæk 2014) was proposed as a basic taste from a fundamental discovery of large amounts of a specific substance, mono-sodium glutamate, in a large brown species of the Laminariales, namely konbu (Saccharina japonica). This discovery goes back to 1908 when the Japanese chemist, professor Kikunae Ikeda, set his mind to figure out what makes Japanese soups taste umai (Ikeda 2002 ).
Professor Ikeda had studied in Europe from 1899-1901 with the famous German chemist Friedrich Wilhelm Ostwald, later Nobel Laureate and one of the founders of the then new scientific discipline physical chemistry. When coming back to Japan, Ikeda studied quantitatively the composition of the famous Japanese soup broth, dashi, which is not only the basis of all Japanese soups but constitutes the center around which the entire classical Japanese cuisine revolves (Tsuji 1980). The Japanese also have a long tradition for making taste infusions of seaweeds, that is teas, e.g., konbu-cha, and in modern Japan you can go and visit dashi bars where you can enjoy infusions of different kinds of konbu.
The recipe for making dashi involves making an aqueous extract of konbu and combining it with an extract of a highly processed fish product, katsuobushi (or shiitake mushrooms if you are a vegetarian). Ikeda found that konbu contains more that 3% of the dry weight as mono-sodium glutamate in free form. He asserted that this substance is the source of the deliciousness of dashi. But he did more than that: he suggested that the taste of MSG is so special that it cannot be produced by a combination of the four classical basic tastes. Hence it elicits a new basic taste that he termed umami (Ikeda 2002 ). It would take almost a century before umami was recognized by the international scientific community as a basic taste proper subsequent to the finding of the first umami receptors (Chaudhari et al. 2000; Nelson et al. 2002).
Hence delicious taste, i.e., umami, is intimately connected to seaweeds. So don’t tell me that seaweeds cannot be taste.
Umami taste of Nordic seaweeds
A few years ago we embarked on a search for Nordic seaweeds with a possible potential for umami and found that the red species, dulse (Palmaria palmate), which is abundant in the North Atlantic waters, has umami taste (Mouritsen et al. 2012). Subsequent analysis in the lab revealed that it contains fair amounts of free mono-sodium glutamate. As collaboration between chefs and scientists we published the results in a scientific journal and convinced the editor that the paper should include three recipes for using a dashi from dulse to provide delicious flavor to ice cream, fresh cheese, and bread.
Dulse as foodstuff is known from a number of coastal regions in Europe, e.g., Ireland, Scotland, Wales, Brittany, and Iceland. It is believed that the when vikings went out to discover North America they brought dry dulse on board the ships as a food supplement to avoid scurvy. In light of our finding that dulse has umami taste it is interesting to note that on Iceland, where dulse 1000 years ago was used as a currency to pay the lease of farms in coastal regions, the dulse that carried the highest currency had fronds with white spots and therefore potentially more umami taste (Mouritsen et al. 2013).
Seaweeds, cooking, and science
Very little has been written and published about the taste of seaweeds and the science behind it (Mouritsen 2012). A number of books have appeared in recent years on seaweeds as edible, versatile, and delicious whole foods and there is a growing focus on using seaweeds in both the daily home kitchen as well as in ordinary and high-class restaurants (Rhatigan 2009; Mouritsen 2013, Lloréns et al. 2016). Some books are cookbooks while others describe nutritional and functional properties of seaweeds as foods (for a list of references, see Mouritsen (2013)). Many celebrated chefs have embraced local seaweeds in their cuisine.
Imagine as a chef to be presented for the first time with the mighty kingdom of algae and what this kingdom add to the usual animal and plant kingdoms used in most cuisines. Mind you, that the algae, the microalgae and the macroalgae together, by far represent the largest biomass on our planet. And when it comes to the large marine algae, the 10,000 different species is a monumental addition to anyone’s cuisine. Then add to this that very few seaweeds species are poisonous to humans.
Maybe it is time not just to say seaweeds when we talk about them as foodstuff. After all, when we talk about food and the taste of food from the kingdom of plants, we don’t just say that we eat plants. We certainly distinguish when it comes to taste between, e.g., tomatoes, corn, hazelnuts, beans, and apples.
Changing people’s mindset about seaweeds
It is my own impression that the interest in seaweeds as whole foods is on the rise in the Western world. Many people know that seaweeds are edible and also healthy food. More and more now also appreciate that seaweeds can be tasty and delicious food. And as I stressed before: taste comes first. If it does not taste good, people won’t eat it.
But it is also a matter of changing peoples’ mindset to consider seaweeds not as ‘weeds’ or ‘wracks’ but as a very versatile, delicious, and tasty kind of food source.
An amusing example from Denmark of how ordinary peoples’ perception can change when it comes to seaweeds is a product called Cavi-art that was invented by a Danish industrialist Jens Møller more than 25 years ago. The first series of Cavi-art products were meant to be a vegan substitute for fish roe, with a good flavor profile, interesting texture, and long shelf-time. The product is based on a kind of spherification (Fig. 4), using different brown seaweed materials and their capacity to form hydrogels via their alginate content. (As a side remark it can be noted that this was a long time before famous chefs made a million-dollar business out of selling seaweed extracts for use in molecular gastronomy.) When Jens Møller first launched his product line, the fact that it was based on seaweeds only appeared in small print on the label on the backside of the containers. In recent years, the design of the labels has changed: it now carries the word seaweed in large font on the very front. Seaweeds have become a positive word.
It starts with children
Proper knowledge with the ordinary consumer about seaweeds as foods and how to prepare them is in this context extremely important. And in some ways it starts with the children.
Let me therefore finish with an example from last week (June 17, 2016) where I was taking part in a large national folk festival at the island of Bornholm in the Baltic Sea. I am currently director of a large Danish center for taste, Taste for Life, whose mission is to convey knowledge about taste to children and young people. We so to speak want the kids to gain ownership to their own senses, in particular taste. For that purpose I often use seaweeds as a less well-known foodstuff and let the kids play with them to produce different kind of dishes. So at the festival last week the kids made a taste and crunchy seaweed salad based on blanched bladder wrack harvested at the local foreshore. Once the kids see how the brown color of the weeds turns beautifully light green, they get curious, and their courage to taste it is highly increased (Fig. 5).
Those weeds are indeed tasty.
The author’s work is supported by Lundbeckfonden (re: R95-A10447) and Nordea-fonden via a grant to the Danish National Center for Taste Smag for Livet.
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Mentioned in the article
Dr Ole G. Mouritsen is head of centre in Taste for Life and head of the Gastrophysics focus area. He is a professor in Gastrophysics and Food Innovation at the Department of Food Science, University of Copenhagen.
He is an expert in bio- and gastrophysics with a special focus on mediation of the natural sciences to the general population through knowledge about food and taste.