Use of Vietnamese seaweed for food, medicine and as biofertilizers

Vietnam has a coastline of approximately 3, 260 km, and the climate varies from subtropical in the northern part to tropical in the southern part of the country. Therefore, it has an abundance of algal flora, with the total number of species estimated to be nearly 1000 spp., of which 638 species of seaweed have been identified (229 Rhodophyta, 123 Phaeophyta, 145 Chlorophyta, 76 Cyanophyta). Traditional harvesting and utilization of seaweeds by Vietnamese coastal people has occurred for over one hundred years. Some of the major economically important seaweed groups can be used for food (human and animal), as material for industry, traditional medicine and biofertilizers/manures. In this paper, the authors analyzed some representative seaweeds of Vietnam included green, brown and red algae. The proximate compositions as ash, protein, lipid, carbohydrate, fatty acids, vitamins, pigments, macro and micro-elements were compared among the different species examined. The present study provides evidence that Vietnamese seaweeds are very rich in protein, lipids (especially polyunsaturated fatty acids), vitamins, pigments, and macro-and micro-elements, and can be used as food to prevent hyperlipidemia, as vegetable and as a functional food. Porphyra crispata, P. suborbiculata, P. veitnamensis, Gracilaria asiatica, and G. eucheumoides are eaten as raw vegetables, or pickles, or prepared for jellies or soups. In southern and Central Vietnam, Gracilaria or Gelidiella species are simmered with added acid and then filtered and cooled into a jelly, known as 'xu xoa'. Gracilaria eucheumatoides is used as an ingredient for soft candy. Gracilaria is also cultured in Vietnam. Ulva sp. is gathered along the coast of central Vietnam. It is fried with pork or beef and also used an ingredient for soup. The Sargassum drink known as 'Tra rong bien' is very popular, and its stalls are frequently seen not only in Southern Vietnam but also in the Central cities such as Nha Trang, Buon Ma Thuot, Tuy Hoa and Quang Ngai. Sargassum species are used as traditioanl medicine, an influence of Chinese culture. Laminaria is used as an ingredient for 'Chi', particularly in Southern Vietnam. Laminaria species do not grow in Vietnam, which is located in subtropical to tropical zones. Sargassum spp. are used for treating goiter or ailments due to iodine diseases. Ulva lactuca and U. reticulate, the name more common species on the coast from central to southern Vietnam, are sold for use as traditional medicines. In industry, Gracilaria spp., Hypnea spp., Sargassum spp., and Kappaphycus spp. are sources of material of agar, carrageenan, and alginate processing. Furthermore, in agriculture, many species of seaweed (mainly brown algae) such as Sargassum spp. and Turbinaria spp. are used as biofertilizers and manure for crops of sweet potato, onion, garlic, and grain. In recent years, the production of fertilizers using manure and Sargassum has developed rapidly in Vietnam.