The increasing use of seaweeds in European cuisine led to cultivation initiatives funded by the European Union. Ulva lactuca, commonly known as sea lettuce, is a fast growing seaweed in the North Atlantic that chefs are bringing into the local cuisine. Here, different strains of Arctic U. lactuca were mass-cultivated under controlled conditions for up to 10 months. We quantified various chemical constituents associated with both health benefits (carbohydrates, protein, fatty acids, minerals) and health risks (heavy metals). Chemical analyses showed that long-term cultivation provided biomass of consistently high food quality and nutritional value. Concentrations of macroelements (C, N, P, Ca, Na, K, Mg) and micronutrients (Fe, Zn, Co, Mn, I) were sufficient to contribute to daily dietary mineral intake. Heavy metals (As, Cd, Hg and Pb) were found at low levels to pose health risk. The nutritional value of Ulva in terms of carbohydrates, protein and fatty acids is comparable to some selected fruits, vegetables, nuts and grains.
Digital library
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Polysaccharides from the brown seaweed Himanthalia elongata and the red one Gigartina pistillata have been extracted by sequential fractionation based on the solubility in water (F-H2O), hydrochloride acid (F-HCl) and potassium hydroxide (F-KOH), remaining a residue (RES). Their structures have been studied through Fourier- transform infrared spectroscopy (FTIR) and molecular weight by molecular exclusion (HPSEC). Sugar compo- sition and sulphate content were also determined. F-H2O and F-HCl from Himanthalia elongata were rich in fucoidans with an estimated Mw of 926 and 430 × 103 g/mol. Laminarans appeared in the mentioned fractions and possibly xylofucoglycuronans and xylomannans are in F-H2O. F-HCl was poorly fermented with low pro- duction of total short chain fatty acids (SCFA) and two poor or non-fermentable low-molecular weight poly- uronans (68 and 4 × 103 g/mol) appeared in F-KOH. Carrageenans extracted from Gigartina pistillata presented low or non-fermentability. Xylofucoglycuronans and xylomannans, possibly presented in RES and F-H2O from Himathalia, and laminarans in the last mentioned fraction, seem to be more fermentable. Carragenophytes red seaweeds do not seem to be fermentable whereas brown algae could have major potential fermentability, probably due to the presence of laminarans, xylofucoglycuronans and/or xylomannans.
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There is practically no reference which gives a complete account of the mineral constituents of the commercial seaweeds and their relationship with the organic constituents or on the- ionic exchanges taking place between the algae and the surrounding water. The early attempts to utilize seaweeds for the manufacture of potash and iodine provide some data on the amounts of these elements and their seasonal variations in particular species. Work on British seaweeds has shown (Chapman, 1950) that the changes in the iodine content are nearly directly proportional to the potash and that the amount of these nutrients in the living plant varies from month to month.
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Several interesting studies have been made in the past on the nitrogen metabolism in seaweeds. Haas and Hi11 (1931) and Haas, Hill and Karstens (1935) isolated water-soluble peptides from the brown alga Pelvetia canaliculata and explained their presence as due to lack of metabolic balance traceable to either desiccation or low illumination. To obtain further evidence Haas, Hill and Russel-Wells (1938) examined the calcareous algae Corallina squamata Ellis, Lithophylum incrustans Foslie, Amphiora capensis Aresch and Galaxaura subverticillata Kjell. A number of unencrusted algae were also examined, but so far among the latter group peptides were found only in the two species, Pelvetia canaliculata and Griffithsia flocculoses. It was found that the encrusted forms contained crude peptides to the extent of 0.05 to 0.29% of the dry weight.
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Seaweeds in general derive their importance from their carbohydrate content. Part of the carbohydrate is in the form of cellulose which cannot be hydrolysed by ordinary means; and the rest in the form of polysaccharides either as agar or as algin, the latter being considered as a polymerised form of d-mannuronic acid. Kylin (1913) is of the opinion that simple reducing sugars constitute the first products of photosynthesis and that they occur in very small quantities.
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PDF on final report of 'Preliminary Study - Chinese Market for Seaweed and Carrageenan Industry'.
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Chondrus crispus, or Irish moss, is a common edible red seaweed that can be found on rocky shores in the Northern Atlantic. The cell wall contains carrageenan and C. crispus is the original source of this commercially used thickener. Because of the ecological and economic importance of this red alga a relatively important research literature exists and one of the recent achievements in C. crispus research is the sequencing of its genome. In this chapter we review some of the literature with the aim to promote C. crispus as a model organism for florideophyte red seaweeds. We consider subjects like commercial and historical uses, ecology, genetics, population structure, mating systems, physiology, cell wall biology and genomics.
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A preliminary classification of five macroalgae from the British Isles; Fucus vesiculosus, Chorda filum, Laminaria digitata, Fucus ser- ratus, Laminaria hyperborea, and Macrocystis pyrifera from South America, has been presented in terms of a Van Krevelen diagram. The macroalgae have been characterised for proximate and ultimate analysis, inorganic content, and calorific value. The different options for thermal conversion and behaviour under combustion and pyrolysis have been evaluated and compared to several types of terrestrial bio- mass including Miscanthus, short rotation Willow coppice and Oat straw. Thermal treatment of the macroalgae has been investigated using thermogravimetry (TGA) and pyrolysis-gc-ms. Combustion behaviour is investigated using TGA in an oxidising atmosphere. The suitability of macroalgae for the different thermal processing routes is discussed. Ash chemistry restricts the use of macroalgae for direct combustion and gasification. Pyrolysis produces a range of pentosans and a significant proportion of nitrogen containing com- pounds. High char yields are produced.
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A PDF Power Point on "Climate: the case for marine bioenergy in Europe and The Crown Estate's response in the UK".
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The coral reef ecosystem forms part of a ‘seascape’ that includes land-based ecosystems such as mangroves and forests, and ideally should form a complete system for conservation and management. Aquaculture, including artisanal fishing for fish and invertebrates, shrimp farming, and seaweed farming, is a major part of the farming and gleaning practices of many tropical communities, particularly on small islands, and depends upon the integrity of the reefs. Climate change is making major impacts on these communities, not least through global warming and high CO2 concentrations. Corals grow within very narrow limits of temperature, provide livelihoods for millions of people in tropical areas, and are under serious threat from a variety of environmental and climate extremes. Corals survive and grow through a symbiotic relationship with photosynthetic algae: zooxanthellae. Such systems apply highly co-operative regulation to minimize the fluctuation of metabolite concentration profiles in the face of transient perturbations. This review will discuss research on how climate influences reef ecosystems, and how science can lead to conservation actions, with benefits for the human populations reliant on the reefs for their survival.
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