Microalgae cultivation

Spirulina: properties and cultivation methods


Spirulina is THE super food that everyone is talking about. It is part of the 4 microalgae autorised today in the food industry. Full of benefits, why does it create so much enthusiasm?

What is spirulina?

Spirulina is a 3.5-billion-year-old filamentous cyanobacteria. Yes, you have read correctly, spirulina isn’t strictly speaking a microalga because its genetic information isn’t stored in a nucleus. It is a prokaryote organism. Contrary to Chlorella, for example, which is a eukaryote organism, that means it has a nucleus. And if you wish to know more on how to cultivate chlorella, follow the link.

Spirulina is the common name given to Arthrospira platensis. It acquired its current name thanks to its recognizable form in a spiral of approximatively 10 micrometers, which is approximatively 5 times smaller than the diameter of a hair as you can see on the photo below.

We also find it mentioned as part of the “blue algae” because of its specified pigments tainted with blue-green just like phycocyanin.

Spiruline au microscope

Microscope view of spirulina

Spirulina consumption

Once cultivated and harvested, there are several ways to use spirulina: either fresh and with still a lot of water, sometimes just rinse (in the form of spread), or dry after a period of time in a proofer for example (capsules, flakes, or in the form of “noodles”). It can be consumed alone, sprinkled on different food or added as an ingredient in different recipes of sweet or salted dishes.

While very trending right now, it is not a new kind of food. The Mayas and the Aztecs used to cook recipes with spirulina as a main ingredient. They called it “tecuitlatl” way before the arrival of the Spanish at the XVI century.

Regular consumers of algae, these civilizations harvested spirulina at the water surface in lacs and then left it in the sun to dry.
Spirulina is still mainly eaten in Africa in countries like Tchad or Niger in most of the local food.

Spirulina, the super-hero of microalgae

If spirulina has this success today, its for its wonderful nutritional properties.

Spirulina, stronger than Popeye’s spinach

Natural and easy to produce, 100 grams of spirulina contain 63 grams of proteins against 22 grams for chicken and 13 grams for the same quantity of egg. It is nutritionally complete. Besides having the highest rate of proteins of any food, it is also very rich in polyunsaturated fatty acids (aka the good fatty acids), in vitamins such as B1, B6 and B12 and also in iron.

Spirulina is recommended to fill nutritional deficiencies such as anemia (du to its iron content), for sportsmen to recover after a physical activity and the synthesis of red cells (vitamins B6 and B12) or only to be in shape daily!

Spirulina and the fight against malnutrition

With its wonderful nutritional properties, spirulina has obtained an important role in the fight against malnutrition. In the 60s, the WHO and UNICEF recognized and underlined the interest of spirulina for human nutrition. Several associations mobilized to put in place centers of productions in countries fighting malnutrition. These measures created jobs for the local population and spirulina was distributed as a food supplement.
Today, the global production of spirulina has reached 5 million kilograms cultivated. In France, we produce about 70 tons per year. It is the microalgae that has the record of number of kilos cultivated (in France).

The different systems for producing spirulina

It is possible to cultivate this microalgae with different systems, the artisanal way or the industrial way. Photobioreactors and raceways are a couple of the most known technologies.

Raceways, the traditional system

Raceways or pound are cultivation systems that are easy to put in place. They are fit for only a few species that can stand cultivation in pound just like spirulina. They are generally rectangle with rounded corners. There is a divider in the middle to place an agitation system such as a wheel. These systems need an important ground space available, a lot of water and are dependent of weather and seasons (for temperature and sunlight). Access to light for spirulina is low on such system and so productivity is also low. When the pounds are open, contamination also need to be controlled to provide an alga of quality.

Photobioreactors, the innovative method

Photobioreactors are closed cultivation systems optimized to cultivate any microalgae and protect from any external contamination. Producers control the cultivation parameters such as pH, temperature or light. This production tool is far less cumbersome and eases the launch, the follow-up and the harvest of the culture. It also responds well to the need for quantity and quality.

At Synoxis algae, we offer a technology with a smooth agitation by airlift called “SALT”. SALT is created by a spiral movement in a tubular system. This allows the microalgae to evolve in an environment that stimulates their development: increased access to light, longer longevity of the cultures (especially in the case of a continuous culture)… SALT technology avoids the apparition of biofilm, obtains higher concentrations and avoids any contamination due to external elements. This technology is perfectly suited for the cultivation of spirulina but also to produce inoculum. We obtain rates of 8 grams per liter of dry mass, almost 8 times more than in a pound !

If you wish to hear more about this technology…. Contact us to explain to us your project and your needs of production!

Photobioreactor in spirulina cultivation