Tuesday, February 12, 2013

Seaweeds: Vegetables of the Sea

Dr Abe V Rotor

Author (top, right) leads UST students in Phycology (study of algae) in a field research at Bacnotan, La Union

Food of the gods.” This is what the ancient Greeks call a special kind of seaweed which the Chinese and Japanese call “food of the emperor.” And only members of the royalty have the exclusive right to partake of this food. It is Porphyra nori to the Japanese, laver to the Europeans, and gamet to Ilocanos.

Thus elevating the status of some 30 species of edible seaweeds to a premium class of food - sea vegetables. The fact is seaweeds have a wide range of importance from food and medicine, to the manufacture of many industrial products. In nature, seaweeds together with corals and sea grasses, constitute the pasture and forest of the sea, a vast ecosystem, unique in its kind because it is the sanctuary of both marine and terrestrial life, and in the estuaries.

Lately however, we have intruded into this horizon, pushing agriculture beyond land towards the sea. We build fishponds, fish pens and cages, resorts, and we introduce poison from our wasteful living.

And yet we have barely discovered the many uses of seaweeds. Ironically we are indiscriminately and unwittingly destroying the very production base of this valuable resource before we have discovered its full potential – in the same way we are destroying the forest even if we have studied barely 10 percent of the potential value of its composition.

A happy note however, may be found in our success in cultivating seaweeds even before naturally occurring species and stands become exhausted. Seaweed farming has been established in coves and sheltered coral reefs such as in Danajon Reef between Cebu and Bohol, on flat coral beds in Calatagan in Batangas, Zamboanga and Tawi-tawi, to mention the most important plantations. Eucheuma, the source of carageenan is the main crop, followed by Gracillaria, Gellidiella and other species as source of algin and agar.

These seaweeds built a multi-million dollar industry locally. Their extracts have revolutionized the food industry, mainly as conditioners in food manufacture. More and more products are derived from them for our everyday use, which other than in food, are used in the manufacture of medicine and drugs, cosmetics, fabrics, paints, films, to mention a few.

Unlike land plants, no seaweed has been found to be poisonous or pathologic. On the contrary seaweeds are rich in minerals and vitamins, which make them elixir of health. Only one species so far is known to cause dizziness when taken in excess - lato or Caulerpa. A substance responsible to this effect is caulerpin, which may be explored of its potential value in medicine as natural tranquilizer.

Sargassum is the most common tropical seaweed. 

Seaweeds, botanically speaking, are not true plants, but rather algae – giants among their counterpart in the micro-world such as the Chlorella and Spirogyra. Biologists have assigned seaweeds into classes based on their color or dominant pigment, hence green (Chlorophyta), brown (Phaeophyta) and red (Rhodophyta). In terms of niche, these three groupings grow naturally at varying depths - in increasing depth in this order. This is ecologically advantageous and definitely a tool in their evolutionary success.

Food Value of Seaweeds

Fishes that feed on seaweeds contain high levels of Vitamins A and D in their liver, apparently absorbed from the seaweeds. Algae also synthesize appreciable amounts of Vitamins B12, C and K. Another advantage they have over land plants is their rich content of iodine, bromine, potassium, and other chemicals that have been discovered recently, many of which have potential value to medicine and industry.

It is no wonder why people who take seaweeds as regular part of their diet are sturdier and healthier and seldom get sick of anemia, goiter and scurvy. It is an observation that the Ilocanos who are the country’s top consumers of seaweeds generally enjoy good health and long life.

The cultivation of other edible seaweeds now include Enteromorpha, Monostroma, Laminaria, Porphyra and Undaria. The importance of seaweed culture is fast expanding this century, principally for food. This is to show the food value of seaweeds using kelp as a model.

Kelp (Laminaria japonica) contains the following nutrients based on a 100-gram sample: Carotene, 0.57 mg; Thiamine, 0.09 mg; Riboflavin, 0.36 mg; Niacin, 1.60 mg; Protein 8.20 g; Fats, 0.10 g; Carbohydrates, 57 g; Coarse fiber (roughage), 9.80 g; Inorganic salts, 12.90 g; Calcium, 1.18 g; Iron, 0.15 g; and Phosphorus, 0.22g.

Philippine seaweeds which approximate the food value of Laminaria are Eucheuma, Gracillaria and Gellidiella. On the other hand, gamet or Porphyra has the following food value. Based on a 100-gram sample, gamet contains protein, 35.6 g; fat, 0.7 g; carbohydrates, 44.3 g; provitamin, 44,500 IU; Vitamin C, 20 mg; Vitamin B1, 0.25 mg; Vitamin B2, 1.24 mg; and Niacin, 10 mg.

Seaweeds Sold in the Market

These seaweeds are commercially sold in Metro Manila, mainly in public markets and in talipapa.

1. Lato or Arusip [Caulerpa racemosa)(Forsk)L Agard], Chlorophyta
2. Guso (Eucheuma sp.), Rhodophyta
3. Gulaman (Gracillaria verrucosa), Rhodophyta
4. Kelp (Laminaria sp.), Phaeophyta
5. Gamet (Porphyra crispata Kjellman ), Rhodophyta
6. Kulot [Gelidiella acerosa (Forsk) Feldman ]

Lato or Caulerpa is of two commercial species, C. racemosa which is cultured in estuaries and fishponds and and C. lentillifera which is usually found growing in the wild. It is the racemosa type that predominates the market. Because of frequent harvesting of this species by local residents lentillifera it is no longer popular in the market. Besides, the cultured Caulerpa is cleaner and more uniform. It has lesser damage and is less pungent than its wild counterpart.

Guso or Eucheuma cotonii is cartilaginous and firm as compared with Caulerpa and because it is very much branched air can circulate better in between the fronds, which explains why its self life may extend up to 3 days. Guso is eaten in fresh state mixed with vegetables or cooked in water and sugar to make into sweets.

Gracillaria verrucosa and G. coronipifolia are the two common species of gulaman. The thallus is bushy with a firm fleshy texture. It is cylindrical and repeatedly divided into subdichotomous branches with numerous lateral proliferation. Gulaman grows up to 25 cm long and has a disclike base. It is found growing in protected, shallow waters.

Gamet or Pophyra crispata Kjellman has a deep red thallus which is flat and membranous with soft gelatinous fronds. Three to nine blades usually form clusters which grow from a very small adhesive disc which has tiny rhizoids attached to the rocky substratum. Gamet grows on rock promontories and rocks exposed directly to the action of waves and wind. This can be observed along the coast of Burgos, Ilocos Norte, which is the major producer of gamet. To date we have not succeeded in culturing gamet in spite of our knowledge on how nori, a species of Porphyra similar to our own gamet, is raised on marine farms in Japan and other parts of the world. The most authentic reason is because the natural habitat of Porphyra is temperate.

Why gamet grows along the northern most tip of Luzon is because the cold Kuroshu Current coming down from Japan reaches this point during the months of December to February. The current probably carries also the reproductive parts of the organisms, which explains the similarity of the Japanese and Philippine species.

Gamet is sold in dried form, compressed in mat, either circular with a diater of 20 to 30 cm, or rectangular in shape measuring some 50cm x 100 cm. Gamet is blanched with boiling water and allowed to cool before salad garnishings are added. It is also added to soup or diningding.

Kulot or Gelidiella acerosa (Forsk) Feldmann and Hamel has tough and wiry thalli, greenish black to dull purple in color. They lie low and creeping on rocks and corals along the intertidal zone. It is very much branched when mature with secondary branches cylindrical at the base and flattened towards the tip and beset on both sides with irregular, pinnately short branches. The fertile branchlets have conspicuous swollen tips.

Kelp or Laminaria is also found in the market. This is popular seaweed growing only in temperate seas. The main supplier is China. Kelp grows to several feet long and is usually thick and broad. It is sold in dried form or cut into strips and soaked in water and rehydrated.

As a source of nutrition and natural medicine, seaweeds are important in commerce and industry and as direct source of food of the people. On the point of ecology, protection of seaweeds in the wild, as well as their cultivation on reefs, farms and estuaries should be integrated under a sound management program of our coastal areas. Thus preserving God’s Eden under the Sea. ~
Codium or pokpoklo is popular among Ilocanos as fresh salad

A species of Caulerpa has became invasive  in the Mediterranean like weed in a field.   
Corals and algae for a symbiotic relationship, that one cannot exist without the other.

No comments: