124. In a special address to the Fifth International Seaweed Symposium, 1965, Dr. F.W. Woodward1 concluded that “Of one thing we can be certain - the rate of growth and development of the seaweed industry in the next 50 years will be far greater than that during the first half of this century”.
1 The Arthur D. Little Research Institute, Inversek, Scotland
125. Although the prospects for wider or more direct use of algae in human nutrition and in medicines must be regarded (despite much optimistic speculation) as rather limited, there are clearly prospects of continued growth in demand for phycocolloids and similar seaweed products. The developed nations of the world are consuming increasing quantities of polysaccharides of all kinds for an almost bewildering range of food, pharmaceutical and industrial applications. In the U.S.A. alone, some half million tons of gums of one kind or another are now utilized annually, recent rates of growth in demand for these products being of the order of 8 to 10 percent annually.2
2 Whistler, R.L. In Whistler (1973)
126. The existing applications for polysaccharides are so numerous and so diverse that together they constitute a market, which is not only substantial but expanding and basically strong. A comprehensive list of these applications, moreover, would resemble very closely a catalogue of the needs of consumer-oriented, economically developed societies - ranging from speciality foods, drink preparations, cosmetics, detergents (and the necessary cartons and wrapping materials) to building materials, paints, textiles, automobile products, oil drilling lubricants and many other industrial products. Thus, as more and more nations progress toward greater economic and social development, so too will the demand for these products - and their constituents - expand quantitatively and geographically.
127. Polysaccharides rarely constitute a complete, finished product but are used principally as additives to improve or control the properties of such commodities. The use of a particular gum is, thus, chiefly influenced by its chemical composition. Economic factors - such as the relative cost of a given polysaccharide, the stability of that cost, the constancy of quality and an assurance of supply - are also very important considerations.
128. In this general market for polysaccharides, phycocolloids compete with seed gums, such as guar gum and locust bean gum, with plant exudates (for example gum arabic), pectin and other plant extracts, starch and cellulose derivatives and various bio-synthetic gums, and can frequently offer distinct chemical and economic advantages.
129. For example, whilst seaweed gums are, in general, higher in unit price than most other polysaccharides, they very often prove more economic to apply than their lower-priced competitors. Phycocolloids can be used in very low concentrations, particularly carrageenan, which moreover possesses unusual abilities to react with the materials with which it is mixed. As Silverthorne and Sorensen (1971) have remarked, “Although synthetic substitutes and natural gums are available, the rapid growth in the demand for carrageenan attests to its unique qualities”. Similarly, agar has proved to be better suited for use as an all-purpose culture medium than most other natural or synthetic polysaccharides and thus has a special position in pharmaceutical and associated markets. Again, algin's highly complex chemical structure gives it unusual properties as a thickening, stabilizing, gelling and emulsifying agent; its price has also been relatively stable and as a result alginates have secured significant shares of a wide range of markets, especially for industrial applications.
130. At the same time it must be observed that intrinsic factors, as well as extraneous influences, will be of considerable importance. Woodward (1966) noted that the growth experienced in the phycocolloid industry was due in large measure to the development of new uses and new secondary products, and remarked that the industry is, and always has been, science-based, every new commercial venture having followed a scientific discovery or extensive research. This search for new sources of chemically and economically useful phycocolloids will have to be continued if the industry is to maintain its share of the polysaccharide markets. The commercial development of furcellaran is a striking example of successful efforts in this direction. On the other hand, mannitol derived from brown seaweed has so far failed to compete with that obtained synthetically from sucrose and, notwithstanding considerable efforts, no significant cost-economic use has yet been found for laminarian or fucoidan. Moreover, the variability in weed quality, in particular gel strength content, of Hypnea has so far prevented hypnean from realizing the potential earlier expected.
131. Recent trends have indeed highlighted the dangers of internal volatility in the phycocolloid markets, particularly that for agar. The remarkably sustained growth experienced by the phycocolloid industry over the last two or three decades has tended to mask the insignificance of phycocolloid output in relation to the total world supplies of polysaccharide gums. The end uses may indeed be manifold and phycocolloids may in certain instances possess specific chemical and economic advantages, but recent events in the agar markets have illustrated the problems arising from over-heavy dependence upon demand from a very few major users, from rising raw material and production costs and from the concentration of output in the hands of a relatively small number of suppliers.
132. The rapid rise in agar prices experienced in 1974 appears to have been caused by a multiplicity of factors. The increase can be attributed partly to the effects of worldwide inflationary trends, partly to rising raw material costs and partly as a consequence of international commodity hedging. Political difficulties in certain key areas of production and suspicions of a measure of market manipulation by a number of traders have also been suggested as important influences.
133. The complexities of the situation were further compounded by the virtual withdrawal from the agar market of one of the world's single greatest customers, followed by a sudden but fairly short-lived emergence of a new use for agar in one of the major markets. As a result, the agar markets in 1975 have been in a very confused state, with a number of traders left holding considerable, expensively bought stocks, nominal quotations for spot or short delivery agar remaining high (about U.S.$ 10 to 11 per kg) but very little actual trading apparently being done. The generally low level of overall economic activity in many of the major markets has also been a factor and indeed has been reflected in a weakening in demand for phycocolloids in general. A securely based recovery in demand will largely depend upon an upturn in world trade, but the events of the last few years may well have left agar in the position of “poor relation” to carrageenan, furcellaran and the alginates.1
134. In general, however, whilst a recurrence of similar cyclical swings is not unlikely, it would seem reasonable to anticipate further long-term growth in the total demand for phycocolloids - at a rate perhaps equal to that of the markets for polysaccharides in general - which in turn will reflect worldwide economic and social trends.
135. The growth in demand for edible seaweed products in Japan and certain adjacent markets shows few signs of slackening even in the face of rising standards of living (which in the West have been generally associated with the virtual disappearance of algae as a food supplement). The traditions and tastes acquired seem likely to maintain consumption of seaweeds at high levels in these countries in the foreseeable future.1
136. Observing the special role of seaweeds in the diets of such important eastern communities, the question is sometimes asked whether algae could not make a bigger contribution to human nutrition in other parts of the world.
137. This possibility may perhaps be best considered under three headings - the nutritional value of seaweeds, their cost-competitiveness relative to other foodstuffs and the question of acceptability and tastes.
138. Most seaweeds are not effective as a source of energy. They are low in fats and generally contain a high percentage of carbohydrates; in this sense they are not dissimilar to such vegetables as lettuce and celery as roughage agents. However, their carbohydrates are for the most part complex polysaccharides which cannot be easily digested by humans.
139. The greatest nutritional value of the algae is in their content of various vitamins, minerals and trace elements.2 Chapman (1970) states that 100 g of algae provide more than the necessary daily human requirements of vitamins A, B2 and B12 and two thirds of those of vitamin C. The food values of seaweeds vary, of course, from species to species. Porphyra, Japanese “nori”, has a high content of protein (between 25 and 30 percent of dry weight), vitamins and mineral salts, especially iodine;3 three quarters of the protein and carbohydrates are digestible by human beings (Schachat and Glicksman, 1959). Other edible seaweeds, for example, dried Undaria (“wakame”) 12 percent, and Laminaria (“kombu”), 6 percent, are much lower in protein content.
140. Considerable research has been undertaken over the past two decades into the edible protein potential of cultivated unicellular algae, especially green and blue-green seaweeds. Under suitable growing conditions, Cyanophyceae such as Spirulina maxima and Chlorophyceae such as Chlorella vulgaris have been shown to contain as much as 60 and 50 percent respectively of protein on a dry weight basis (Gordon, 1969).
141. Certain seaweeds thus clearly have significant nutritional value, particularly so far as protein and vitamins are concerned. Moreover, a number of experimental studies have given definite indications that seaweed foods are of greater value to sick or undernourished persons than to those in normal health or on adequate diets4 - a point of interest when considering the potential use of edible seaweeds in regions of malnutrition.
142. In general, however, the poor digestibility of most seaweeds by and large limits their use in human nutrition to that of a food supplement. Prior chemical digestion, it has been suggested, might be a means of providing protein-rich algal foods, but lower-priced competition from more conventional foods and additives would probably make such proposals uneconomical.1
143. The costs of preparing edible seaweed products are indeed very high and rising rapidly. For example, the bulk price for fresh Undaria (the raw materials for “wakame”) in Japan rose from U.S.$ 0.02 per kg in 1957 to U.S.$ 0.25 per kg by 1970.2 Even the cheaper edible seaweed products are considerably more expensive than most other food items.3 Thus, even where they are widely consumed, such products are used mainly as seasonings and as supplements to other dishes rather than as a staple food.
144. Interest has been shown in various parts of the world in the possibilities of using algal protein as a food supplement, for example, when mixed with flour. A number of studies have indeed demonstrated, at least at the experimental level, that the photosynthetic efficiency achievable in algal protein formation is very considerably greater than that possible with conventional animal and vegetable proteins. It has been postulated (for example, Vincent 1969; Bhattacharyya et al., 1971) that from such algae as Spirulina and Chlorella as much as 21 700 lb and 14 000 lb respectively of protein (dry weight) could be obtained per acre per year, compared with protein yields per acre from fish of 560 lb, peanuts 420 lb, peas 353 lb, wheat 209 lb and milk 90 lb. However, algal growth rates have been found to be much lower in practice than in theory or in small-scale experiments, and large-scale cultivation tends to be very expensive; it has been estimated that a final commercial price for extracted algal protein would be approximately U.S.$ 800 per ton.4
145. Moreover, even though such prices would not necessarily prejudice the use of algal protein as a food supplement, there remains the question of consumer acceptance of such commodities. Aside from the problem of poor digestibility, the palatability and appearance of algae such as Chlorella present difficulties as they are slimy in texture and objectionable in colour and flavour. There thus seems to be little immediate prospect of any notable contribution of such products to human nutrition.5
146. Similarly the geographically wider use of edible seaweed products of the “nori”, “wakame”, “kombu” type appears unlikely on the grounds both of cost and of consumer acceptance. In the foreseeable future, therefore, the demand for seaweeds for direct human consumption - whilst substantial and growing - will almost certainly remain restricted to communities where their consumption is already of long tradition.1
147. As already noted in an earlier part of this paper, under presently foreseeable circumstances, no remarkable expansion in the use of seaweed as an animal food supplement appears to be in prospect. Similarly, although certain markets have been developed for liquid seaweed fertilizers, this again seems unlikely to become a major seaweed consuming industry. In general, as observed by Silverthorne and Sorensen (1971), the beneficial effects of the use of seaweeds in agriculture can also be obtained in other ways and so far no evidence has been produced to demonstrate that seaweed products as a whole have any significant cost advantage over alternative methods of feeding or fertilizing.
148. Seaweeds have been long used in many parts of the world as primitive medicines and the value of phycocolloids in the preparation of pharmaceutical products is now well established. Considerable efforts have recently been exerted in attempts to discover more direct therapeutic applications for seaweeds but, despite high expectations, no commercially successful products have yet been developed.
149. Certain seaweeds are known to have properties as expellants of intestinal worms and as anti-coagulants2; surgical uses have been demonstrated for Laminaria (Chapman, 1970); and antibacteriological activity has been documented for a number of algae.3 However, these and various other potential medicinal applications for seaweeds have so far failed to achieve significant use, chiefly because of the existence of cheaper or more effective forms of treatment. There may yet be a breakthrough from the continuing research but direct consumption of seaweed drugs and medicines seems, at best, likely to be relatively small.
2 Anon., Therapeutic Seaweed, Oceanology Int., May/June, 1969, p.22
150. In summary, whilst continued growth in the demand for edible seaweeds can be anticipated from oriental communities, no significant increase seems to be in immediate prospect in the contribution of seaweeds to human nutrition as a whole, nor in their use for agricultural or medicinal purposes. The major expansionary force in the seaweed industry will undoubtedly be further growth in the demand for phycocolloids.
151. The extent to which these demands can be met at competitive prices will depend in large measure upon the availability of raw materials. It is commonly agreed that the seaweed industry's single greatest problem is that of identifying and efficiently exploiting new resources of algae, both of species already utilized and of species so far neglected. The attention being given to improved harvesting techniques, to resource conservation, and, particularly, to seaweed cultivation, is illustrative of the importance of this problem, which is further examined in the next section of this paper.
