Spirulina, dried powder

With 10 g of algae sample, the bowl use to be filled to the maximum when the proper amount of water will be added to maintain a motor oil like viscosity (for an optimum grinding result).

To avoid denaturation of proteins or other ingredients, we ground the sample in steps of 1 minutes, followed by a programmed pausing time of 7 minutes. For a grinding time of 30 minutes, about 4 hours of total processing time are required. If the sample does not use to be temperature sensitive, grinding times can be enlarged or pausing times can be shortened.

After 15 minutes of grinding, the viscosity of sample became very pasty. For this, we have taken out ~ 11 g of slurry and filled separately. About 13 ml of fresh water has been added to the remaining sample inside of the grinding bowl to maintain a motor oil like viscosity again.

We proceeded grinding until the sample has been ground for 30 minutes. By checking with optical microscopy, no intact cells have been observed. Only very small fragments of pieces of algae have been detected.

We used our Laser Particle Sizer ANALYSETTE 22 NanoTec plus to check the particle size distribution. We found a d50 < 730 nm. A proper detection of the present distribution is not possible because Mie parameters are missing. If the proper Mie parameters can be given, a recalculation of the grinding results is possible.

Possibly a high content of proteins also formed a very fine foam which might be able to disturb a proper particle size detection (bubbles will be displayed as particles of ~ 10 µm diameter).

It might be possible achieve a better grinding result by longer grinding time, also a change in ball size (e.g. to 0,5 mm Ø) could be beneficial to improve the grinding result. But most organic compounds cannot be ground into low nano range.