SEAWEEDS AND THEIR APPLICATIONS

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SEAWEEDS AND THEIR APPLICATIONS

• BY
• S.BARATHY SELVARANI
• II M.Sc., MARINE BIOTECHNOLOGY

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• Seaweeds are a fascinating and diverse group of
  organisms living in the earth's oceans.
• You can find them attached to rocks in the
  intertidal zone, washed up on the beach, in giant
  underwater forests, and floating on the ocean's
  surface.
• They can be very tiny, or quite large, growing up
  to 30 metres long!

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CONT.

• Seaweeds are marine algae saltwater-dwelling,
  simple organisms that fall into the somewhat
  outdated, but still useful, category of "plants".
  
• Seaweeds are plants because they use the sun's
  energy to produce carbohydrates from carbon
  dioxide and water (this is called
  photosynthesis). They are simpler than the land
  plants mainly because they absorb the nutrients
  that they require from the surrounding water and
  have no need for roots or complex conducting
  tissues.

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CONT.

• Seaweeds are also called macro-algae. This
  distinguishes them from micro-algae
  (Cyanophyceae), which are microscopic in size,
  often unicellular, and are best known by the
  blue-green algae that sometimes bloom and
  contaminate rivers and streams.
• Three groups of seaweeds are recognised,
  according to their pigments that absorb light of
  particular wavelengths and give them their
  characteristics.

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STRUCTURE OF SEAWEEDS

• Holdfasts
• stipe
• blades
• floats
• thallus

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CONT.

• Instead of roots seaweeds have holdfasts, which
  attach them to the sea floor. A holdfast is not
  necessary for water and nutrient uptake, but is
  needed as an anchor. Holdfasts are made up of
  many fingerlike projections called haptera.The
  stalk or stem of a seaweed is called a stipe. The
  function of the stipe is to support the rest of
  the plant. The structure of the stipe varies
  among seaweeds they can be flexible, stiff,
  solid, gas-filled, very long (20 metres), short,
  or completely absent.The leaves of seaweeds are
  called blades. The main function of the blades is
  to provide a large surface for the absorption of
  sunlight. In some species the blades also support
  the reproductive structures of the seaweed. Some
  seaweeds have only one blade, which may be
  divided, while other species have numerous
  blades.Many seaweeds have hollow, gas-filled
  structures called floats or pneumatocysts. These
  help to keep the photosynthetic structures of the
  seaweed buoyant so they are able to absorb energy
  from the sun.The term thallus refers to the
  entire plant body of a seaweed.

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REPRODUCTION INSEAWEEDS

• Seaweeds reproduce in a variety of ways. Lower
  types reproduce asexually. More advanced kinds
  produce motile zoospores that swim off, anchor
  themselves, and grow into new individuals, or
  they reproduce sexually by forming sex cells
  (gametes) that, after fusing, follow the same
  pattern. Sometimes pieces of a seaweed break off
  and form new plants in a few species there is a
  cycle of asexual and sexual reproduction
  foreshadowing the alternation of generations
  characteristic of plants

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Types of Seaweeds

• PHAEOPHYCEAE Brown algae
• CHLOROPHYCEAE Green algae
• RHODOPHYCEAE Red algae

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PHAEOPHYCEAE

• CHARACTERISTICS
• Marine water species
• Xanthophyll pigment, which masks the other
  chlorophyll and carotenoid pigments.
• food reserves are polysaccharides

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CONT.

• Brown seaweeds are usually large, and range from
  the giant kelp that is often 20 m long, to thick,
  leather-like seaweeds from 2-4 m long, to smaller
  species 30-60 cm long

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CHLOROPHYCEAE

• CHARACTERISTICS
• Also a marine water species
• Chlorophyll a b
• food reserves are starch

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CONT.

• Green seaweeds are also small, with a similar
  size range to the red seaweeds.

Green seaweeds are found on both sandy and rocky
beaches. Many can tolerate low salinity and will
colonise areas where rivers meet the sea. The
green colour of the seaweed is due to the green
pigment chlorophyll required for the
photosynthesis of light.
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RHODOPHYCEAE

• Red seaweeds are usually smaller, generally
  ranging from a few centimetres to about a metre
  in length however, red seaweeds are not always
  red they are sometimes purple, even brownish red
  .

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CONT

• The red colour of the seaweeds is due to the
  larger amount of red phycoblin pigments
  overriding the green pigment chlorophyll.
• The pigments that colour it red have a purpose,
  enabling the seaweeds to photosynthesis light
  from a specific part of the light spectrum.
  Within the group of phycoblins two pigments are
  of importance phycoerythrin and phycocyanin.
  Phycoerythrin absorbs green, yellow and red light
  while phycocyanin absorbs blue, green and yellow
  light. These parts of the spectrum are the type
  of light that penetrates the deepest in sea
  water. The red pigments absorb the light but
  chlorophyll is still required to process it.

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APPLICATIONS

• Used as a food
• Used as a medicine
• Used as a soil fertilizer conditioner
• Alginophytes
• Agarophytes
• Carrageenan
• Animal feed
• Fish feed

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USED AS A FOOD

• Food from brown seaweeds comes mostly from the
  genera Laminaria, Undaria and Hizikia.
• Porphyra species are the largest source of food
  from red seaweeds. Dulse (Palmaria palmata,
  formerly Rhodymenia palmata) is another red
  seaweed used as food.
• Sea Lettuce Ulva lactuca - This is a green
  seaweed which looks similar to a lettuce leaf and
  is edible.

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Medicinal uses

• RESPIRATORY TREATMENT
• Red algae containing carrageenan have been used
  for respiratory ailments, especially intractable
  sinus infections and lingering pneumonias.
  ANTIVIRAL RED SEAWEEDS
• Strong antiviral activity has been observed in a
  variety of heavily modified carrageenans and
  research continues on how to use this in
  commercial medications. One carrageenan
  derivative showed strong anti-HIV activity when
  delivered as a contraceptive vaginal foam.

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cont.

• HORMONES IN SEAWEEDS
• Melatonin is abundant in many seaweeds, up to
  1000 times the amounts found in land plants. This
  may explain some of the calming effects of eating
  seaweeds. There may be some useful therapeutic
  opportunities using seaweed-sourced melatonin.
• Thyroid Hormones in SeaweedsBrown seaweeds are
  the only known non-animal sources of thyroid
  hormones.
• The presence of organically-bound iodine in brown
  seaweeds as thyroid hormones may explain some of
  the effects of eating some brown seaweeds.

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cont.

• ESSENTIAL FAT AND VITAMINS IN SEAWEEDSMost
  seaweeds are rich in vitamins, especially the B
  vitamins, including B12.
• They also have significant amounts (1-3)of
  Omega-3 fatty acids. Nori, in particular has 3
  omega-3 fatty acids and large amounts of vitamins
  A and C.

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cont.

• CARRAGEENAN INHIBITION OF PAPILLOMA VIRUS
  INFECTION

Carrageenan is an easily extracted, sulfated
unbranched polygalactose red algal polymer. It is
used in thousands of patented applications in
food and cosmetic products and in sexual
lubricants.
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SEAWEEDS AS MEDICINE

• Seaweeds as the Best Dietary Sources of Essential
  Minerals
• All essential minerals are provided by dietary
  seaweeds. No land plant even remotely approaches
  seaweeds as sources of metabolically-required
  minerals. Seaweeds are 20-50 dry weight
  mineral(Kazutosi, 2002). The elements abundant in
  seaweeds include potassium, sodium, calcium,
  magnesium, zinc, copper, chloride, sulfur,
  phosphorous, vanadium, cobalt, manganese,
  selenium, bromine, iodine, arsenic, iron, and
  fluorine.

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AGAR

• Most agar is extracted from species of Gelidium
  and Gracilaria

Gelidium
Gracilaria
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cont.

• Food grade agar
• A short and simplified description of the
  extraction of agar from seaweeds is that the
  seaweed is washed to remove foreign matter and
  then heated with water for several hours. The
  agar dissolves in the water and the mixture is
  filtered to remove the residual seaweed. The hot
  filtrate is cooled and forms a gel (jelly) which
  contains about 1 percent agar. The gel is broken
  into pieces, and sometimes washed to remove
  soluble salts, and, if necessary, it can be
  treated with bleach to reduce the colour. Then
  the water is removed from the gel, either by a
  freeze-thaw process or by squeezing it out using
  pressure. After this treatment, the remaining
  water is removed by drying in a hot-air oven. The
  product is then milled to a suitable and uniform
  particle size.

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cont.

• Bacteriological agar
• This can only be made from species of Gelidium
  because the resulting agar has a low gelling
  temperature (34-36C) that allows the addition of
  other materials to the agar with a minimum risk
  of heat damage. Gracilaria and Gelidiella give
  agars that gel at 41C or higher.
• "Bacto" agars must not contain anything that
  might inhibit the growth of bacteria, such as
  trace metals, soluble carbohydrates or proteins,
  nor should they contain any bacterial spores.
  They must not interact with any materials that
  must be added as nutrients for the bacteria under
  study. The gels must be strong and have good
  clarity.

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cont.

• Agarose
• Agar can be divided into two principal
  components agarose and agaropectin. Agarose is
  the gelling component agaropectin has only a low
  gelling ability. There are several methods of
  producing agarose many rely on removing the
  agaropectin from the agar. There are only a small
  number of processors who produce purified, high
  quality agarose for a small but growing market,
  mainly in biotechnology applications. These
  processors use good quality agar as their
  starting material rather than seaweed, and are
  often not in the seaweed processing business.

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ALGINATE

• Ascophyllum, Durvillaea, Ecklonia, Laminaria,
  Lessonia, Macrocystis and Sargassum,

Ascophyllum
Durvillaea
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cont.

• The uses of alginates are based on three main
  properties.
• The first is their ability, when dissolved in
  water, to thicken the resulting solution
• The second is their ability to form gels.
• The third property of alginates is the ability to
  form films of sodium or calcium alginate and
  fibres of calcium alginates.

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TEXTILE PRINTING

• In textile printing, alginates are used as
  thickeners for the paste containing the dye.
  These pastes may be applied to the fabric by
  either screen or roller printing equipment.
  Alginates became important thickeners with the
  advent of reactive dyes. These combine chemically
  with cellulose in the fabric. Many of the usual
  thickeners, such as starch, react with the
  reactive dyes, and this leads to lower colour
  yields and sometimes by-products that are not
  easily washed out. Alginates do not react with
  the dyes, they easily wash out of the finished
  textile and are the best thickeners for reactive
  dyes. Alginates are more expensive than starch
  and recently starch manufacturers have made
  efforts to produce modified starches that do not
  react with the reactive dyes, so it is becoming a
  more competitive market.

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Cont.

• Alginate derivatives of alginic acids, are used
  commercially for toothpaste, soaps, ice cream,
  tinned meats, fabric printing etc.,
• It forms a stable viscous gel in water, and its
  primary function in the above applications is as
  a binder, stabilizer, emulsifier,, or moulding
  agent.

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CARRAGEENAN

• Most carrageenan is extracted from Kappaphycus
  alvarezii and Eucheuma denticulatum
• . The original source of carrageenan was Chondrus
  crispus, and this is still used to a limited
  extent.
• Betaphycus gelatinum is used for a particular
  type of carrageenan.

Kappaphycus alvarezii.
Betaphycus gelatinum
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cont.

• There are several carrageenans, differing in
  their chemical structure and properties, and
  therefore in their uses. The carrageenans of
  commercial interest are called iota, kappa and
  lambda.
• Their uses are related to their ability to form
  thick solution or gels, and they vary as follows.
• Iota- Elastic gels formed with calcium
  salts.Clear gel with no bleeding of liquid (no
  synaeresis).Gel is freeze/thaw stable.Kappa-
  Strong, rigid gel, formed with potassium
  salts.Brittle gel forms with calcium
  salts.Slightly opaque gel, becomes clear with
  sugar addition.Some synaeresis.Lambda- No gel
  formation, forms high viscosity solutions.

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USES PROPERTIES

• Processed Meat, Poultry Seafood - Water
  binding, increased product yields, improved
  texture, fat replacement, meat/seafood analog
  binding, tolerant to high levels of salt.
• Dairy (Chocolate Milk, Frozen Desserts, UHT
  Milks, Flans, Puddings, Low Fat Cheese, Cheese
  Analogs) - Provides cocoa suspension, milk
  stability, emulsion stability, milk gelling.
• Cold Milk Powders (Diet powder mixes, Nutritional
  beverage mixes) - Provides body and mouthfeel,
  suspends solids.
• Water gel Desserts - Provides wide range of
  textures and flavor release, all without the need
  for refrigeration.
• Toothpaste - Provides structure without masking
  flavors, resistant to enzymatic breakdown.
• Pharmaceutical -- provides animal-free capsules
  (soft and hard).
• Petfoods - Binds water, provides structure and
  prevents fat separation in canned retorted
  products, excellent binding.
• Air Freshener Gels - Provides structure and
  controlled release of active ingredients such as
  per fume in a water gel base.
• Beer Fining -- acts as a process aid in beer
  manufacture to produce good clarity.

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CONT.

• Wastewater treatment
• There are two main areas where seaweeds have the
  potential for use in wastewater treatment.
• The first is the treatment of sewage and some
  agricultural wastes to reduce the total nitrogen-
  and phosphorus-containing compounds before
  release of these treated waters into rivers or
  oceans.
• The second is for the removal of toxic metals
  from industrial wastewater.

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CONT.

• Fertilizers and soil conditioners
• Animal feed
• Fish feed
• Biomass for fuel
• Cosmetics
• Integrated aquaculture

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REFERENCES

• www.fao.org/docrep/006/y4765e/y4765e0c.htm
• www.bcb.uwc.ac.za/envfacts/seaweeds/index.htm
• http//www.oceanlink.info/biodiversity/seaweeds/se
  aweeds.html
• www.ryandrum.com/seaweeds.htm
• www.uoflife.com/wc/studentpapers/seaweed.htm -
  www.infoplease.com/ce6/sci/A0861006.htm
• http//www.shemberg.com.ph/carrageenan.html

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