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Microalgae Uses in Human Nutrition: For Making Biodiesel and Colorant



BY: Padma Kumar | Category: Biology | Submitted: 2010-12-04 19:32:18

Biodiesel from Microalgae

The blooming algae millions of years ago are probably one of the contributory factors to the formation of crude oil resources that we currently use.

In recent times making fuel from algae has graduated from the laboratory stage to a technologically ready state. Several research firms and companies are in the fray.

Example

A type of genetically modified blue green algae cyanobacteria actually secretes bio-oils. This means that after growing the algae there is no need to harvest, dry and then extract the algal oils for further processing to biofuels. Sapphire Energy for instance uses this proprietary technology to convert these blue green algae to biological crude which is similar to light sweet crude----and further to liquid fuels using just sunlight and carbon dioxide. The carbon impact is more than 50% less than other fossil fuels.


How can microalgae be used to make biodiesels?

Firstly microalgae are efficient in terms of carrying out the process of photosynthesis. Maximum algal energy is to be found in the chloroplast. The chloroplast uses sunlight and carbon dioxide to make oils that can be refined to common liquid fuels that we use today. The microalgae oils are composed of triacyglycerols or what are referred to as TAG's. This is where the lipids are stored. Using the transesterification reaction (with acid or base and methanol) TAG's can be converted to biodiesel.

Example

The microalgae Botrycoccus braunii is an ideal candidate for biodiesel production and the fuel made from this has calorific value akin to class C fuel

Co-firing microalgae with coal

Co-firing microalgae with coal is probably an exciting proposition as coal and microalgae have some similiraties. Power plants using coal have higher carbon emissions and this can be reduced if microalgae are used in combination with coal.


Why are microalgae an ideal candidate for making liquid fuels including biodiesel?

There are several reasons that make microalgae an exciting feedstock for making biodiesel. They are:

• The primary reason is the fact that yields of oil from microalgae are much higher in comparison with oilseeds. For example, in comparison to canola, microalgae as feedstock can give thirty times more oil on a per hectare basis. For instance, seventy five percent of the dry weight of Botryococcus braunii microalgae (an oily plant that you can see floating as green mats on lakes and other water bodies) is made up of natural hydrocarbons that can be exploited for making biodiesel.

• Microalgae achieve full growth in a short time. There is no need of fertile land or potable water for growing microalgae. In fact it can be grown in the desert in salt water. The most important nutrient for growing algae is carbon dioxide. For every gallon of green crude produced, algae consume 13 to 14 kg of carbon dioxide.


What are the advantages of biodiesel made using microalgae?

It is less toxic as it has lesser emission of carbon monoxide in comparison to diesel.

It can be used in conventional diesel engines without modification and lubricates the engine better.

Biodiesel is biodegradable as the C16-18 methyl esters in them are reckoned to be biodegradable

Biodiesel does not have sulfur. So there is no need to remove sulfur oxides as in conventional diesel. Biodiesel gives out a pleasant odor on burning.

Microalgae in human nutrition

Although the major composition of algae is protein, lipid and carbohydrate in that order its nutritional value depends on certain factors. These are:
• Culture conditions
• Cell size of the algae
• The digestibility of the algae
• The biochemical make up of the algae
• Whether the algae produces any toxic substances

Some strains of microalgae have been used to make nutritional products (usually as tablets, capsules and as snack foods) for human use. They are:

• Arthrospira(used for its high protein content for combating hypertension and high lipid levels---mostly made in China and in the US. Example: The Anthrospira manufacturing plant of Earthrise farms in the US)

• Chlorella (reduces blood lipid levels, works as an immunosuppressant and used for treating wounds and gastric ulcers. It is also used as food additive)

• D. salina (has high beta carotene content) and so can be used to extract beta carotene.

• Aphanizomenon flos-aquae (used as natural health tonic)

• Spirulina is widely used as a nutritional supplement

• Docosahexaenoic acid or DHA is important for cardiovascular health and is usually found in breast milk and some fatty fish. But now Crypthecodinium cohnii and Schizochytrium microalgae can be sourced for this 3-omega fatty acid.


Vitamins

Generally most multivitamin preparations do not contain Vitamin K2. Vitamin K2 activates the inhibitor of arterial calcification, so its intake prevents vascular damage. It is also beneficial in combating heart disease and osteoporosis, varicose veins and Alzheimers. Vitamin K2 can be extracted from Hawaiian Spirulina Pacifica


Antioxidants

Vitamin E is reckoned as a potent antioxidant. But natural astaxanthin extracted from microalgae is several hundred times more potent than conventional antioxidants like Vitamin E and beta carotene. Natural astaxanthin sourced from microalgae is now commercially available as BioAstin(R) and could be useful for treating rheumatoid arthritis and Carpel Tunnel Syndrome.


Making colorants and perfumes from microalgae

Colorants

Several pigments can be found in microalgae species. Research is currently on to find out which of them can be used as substitutes for synthetic colorants that are commonly used in food, beverage and pharmaceutical industry. Some of the pigments found in microalgae are:

• Chlorophyll (green pigment)
• Fucoxanthin (found in brown algae)
• Peridinin (light harvesting carotenoid)

The red microalgae have what are called phycobiliproteins (photosynthetic pigments accumulated in cells) which are algal pigments. These could be red or blue. These algal pigments find use as an alternative to synthetic pigments.

Red color: The natural red color can be extracted from the microalgae Porphyridium cruentum and this has applications in food and beverage sectors. The protein ficoerithrin gives the microalgae red color.

Blue color: The red microalgae Porphyridium aerugineum is the natural source for blue color---and it does not have red phycoerythrin

Fluorescencent pink color: Some microalgae have the B-ficoerithrin making them look fluorescent. The protein B-ficoerithrin can be extracted from this microalgae. Porphyridium are also the source for natural flouroscent pink color.

Beta carotene is an important colorant which can be sourced from the microalgae Dunaliella


Perfumes

Microalgae could be source for making exotic perfumes.

Example
The microalgae Ectocarpus siliculosus could be used for sourcing ectocarpene which has scent similar to tomato leaves.

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