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Spirulina expert Jean-Paul Jourdan


Jean-Paul Jourdan - Spirulina expert

Another highlight of Ashley’s January/February 2012 trip to France, was spending a day with Jean-Paul. He is a chemical engineer by trade and his experience with Spirulina is in the area of maximising production. He previously worked for Technap, a humanitarian organisation to assist the third world with technology, as their Spirulina expert.


Jean-Paul has his own Spirulina website where he has been publishing newsletters for many years:

On this site are all his archived newsletters plus a complete updated growing manual in English, as well as several automatic calculators for nutrient requirements and costings.

In France, Spirulina costs about Euro 30/kg to produce.

Jean-Paul explained the difference in quality between various producers of Spirulina and the most important ingredient for health which is its blue pigment called phycocyanin.  This is a powerful antioxidant as well as providing other health benefits. A good quality Spirulina contains 15% to 20% but a minimum should be 12%. Phycocyanin accounts for 15% to 20% of proteins in Spirulina too.

Some companies in Asia extract the phycocyanin from Spirulina and sell it to the food industry as blue food colouring. They then sell the Spirulina at a lower price to compete on the global market. Jean-Paul wants the market regulated so that Phytocyaninin levels must be put on all labelling. A Japanese company discovered the blue Phycocyanin in the 1980's and set up the first commercial Spirulina growing and processing plant in Japan. They now are the owners of a company that has a huge operation in California. Each of their tanks is 500 square metres. Phycocyanin is sensitive to heat and physical damage which oxidises this phytochemical. This company spray dries Spirulina at 250 degrees C, even if it is for a few seconds. They also have to pre rupture the cells to assist drying. Both processes damage the sensitive Phycocyanin.  Jean-Paul explained that the best method for drying to preserve the Phycocyanins is to freeze dry. Even solar dryers, where the Spirulina is exposed directly to UV, damages the product.

Spirulina should be dried to between 5% and 7% moisture. The maximum allowable is 10%. Dried Spirulina has a shelf life of about 2 years. About a third of the cost of production is related to the drying process.

A simple test for the presence of Phycocyanin is to check the blue colour by dissolving 4 grams of spirulina in 100 mls of water for 10 hours and look for the blue-green colour of this blue-green algae. Apparently there are other blue-green algae but many are poisonous.


Spirulina should be grown at a pH of between 10 and 11 at temperatures of between 35 to 38 degrees with the optimum being human blood temperature of 37 degrees C.

Spirulina can only tolerate 40 degrees C for short periods.

The rate of growth below 30 degrees C is unproductive. Spirulina grows at its optimum at between 10% to 20% full summer sun strength. Spirulina will become light saturated at over1/3 of summer sun strengths.  Death  can occur at low temperatures below 25 degrees C and high light. Low light also produces the highest % of Phycocyanin. Therefore Spirulina must be kept between 25 to 40 degrees.

Expect yields between 6 to 10 grams per square metre per day. A carefully designed thin film Spirulina system with CO2 injection and optimised light and nutrition could yield up to 20 grams per day per square metre. Outdoor production in France and California produce Spirulina 6 to 7 months per year yielding 2 to 3kg per square metre per annum. There is a thin film Spirulina grower under plastic in Simondi, South Africa.

There are currently over 100 Spirulina growers in France, mostly concentrated in the South of France. A large producer has about 1,000 square metres of tanks and one very large producer has a 4,000 square metre operation. 

 Jean-Paul Jourdan beside his home grown Spirulina tank with snow in the back yard

Jean-Paul recommended a 10mm thin film production system which if carefully designed with optimised light, C02 and nutrient could produce up to 20g per square metre per day compared with the standard 200m deep flow systems of 6 to 10 grams per day per square metre.

A 10mm deep thin film system should have a flow rate of 0.36 litres per second per square metre of bed and a holding tank turnover every 30 minutes. The holding tank is usually 8 times the total capacity of the bed. For example if the bed is 10mm deep by one metre square = 10 litres, then the tank should be 80 litres. A typical slope for a thin bed is 1:100 and a maximum of 100 metres long.

Concentration of culture in a thin bed can be twice as high as a standard 200mm deep flow system (0.6 to 1.0 gms per litre Vs 0.3 to 0.5 gms per litre). A higher concentration is less prone to failure due to wild competing algae, particularly at lower media temperatures and high light when Spirulina is under stress. A higher concentration is also more economical to harvest.

One issue that Spirulina has is that alginate polysaccharides build up in the medium which blocks filters. It is a sticky jelly like substance. Many growers regularly dump the media to overcome the problem which is a waste of nutrient and not good for the environment. Jean-Paul has an alternative. The filtrate can be directed into a holding tank where it is then well aerated to encourage aerobic bacteria to break down the alginates, which takes about 2 weeks. This equates to about 20% of the media at each harvest. A series of tanks are required so that each day the filtrate can be directed into a new tank. After two weeks the first tank can be pumped back into the main production tanks and then the other treatment tanks pumped sequentially, ensuring each tank has a two week retention time for adequate treatment. Ensure that no Spirulina filaments enter the treatment tanks as these will build up over time when pumped back into the production tank. Treatment tanks require a lot of aeration and during this time the pH should remain at an equilibrium of 10 which is ideal for Spirulina.

Some growers also dump media when salts build up and the system becomes imbalanced. Jean-Paul has a commuter model on his website that calculates the exact nutrients to add, based on an initial water analysis. He believes in adding individual nutrients little and often.

Calcium is sometimes a problem in France. Excess calcium and magnesium in the make up water precipitates out at a high pH. Calcium is often added to the French water supply at 10ppm to reduce corrosion of steel hot water heating pipes.

Harvesting is done through a 30 micron filter. It is then squeezed to bring the moisture content to about 40% and then squeezed further in a press to reduce the moisture to about 20 %. The Spirulina dough is then squeezed through a press with 1 to 2 mm holes. The Spirulina spaghetti is then placed in layers zig zagged across a drying screen for solar or air drying. Aim at drying for no more than 3 hours with less than 50 degree Celsius heat to 5-7% moisture.

Note that Spirulina is damaged through standard pumps with even medium shear. A vortex type pump must be used.

In France fresh Spirulina is sold at farmers markets. It has no smell or taste and has the maximum nutrients intact, particularly the Phycocyanin. Growers recommend to their customers that they should quick freeze their Spirulina for maximum health and taste. Jean-Paul suggests rolling the Spirulina dough very thinly, and then running cuts almost through the dough then freezing and when required, the customer needs only to break a cube off, similar to a chocolate bar. Fast freezing prevents sharp ice crystals forming which rupture the Spirulina cells and when thawed allows the blue liquid of the Phycocyanin to run out.

Jean-Paul recommends starting a new Spirulina production system with a pure strain number PCC 8005 from the Pasteur Institute in Paris. 

If trialling growing Spirulina in a growth chamber (Phytotron in French), use 12 to 16 hours of light per 24 hours and harvest at 1g per litre in a thin film system.

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