How you get the red out of the green

Algae classification with decanters

Despite minor size differences and in particular minimum density differences, it is now possible for a special decanter to classify green algae. GEA has once more pushed out boundaries, and decanter technology has opened up new areas of application.

Partnership between our customers and GEA

In the past, algae harvest was associated primarily with separator technology; until recently, it was not possible for conventional decanters to be used in these applications. However, in the special case of astaxanthin production, it would not have been possible to separate algae cells of different sizes by using separators as a result of excessive g-forces. The breakthrough was achieved with a trial carried out at the Central Process Engineering (CPT) department of GEA using a specially designed decanter. In this trial, the processing know-how of a biotechnology company was successfully combined with the centrifugation know-how of GEA.

Asthaxantin makes salmon red and has anti-oxidant qualities

Natural astaxanthin is a very valuable pigment which is traded on the world market for a price of several thousand dollars per kilogram. The higher the astaxanthin content in the end product which is in powder form, the better the price. The anti-oxidative effect of astaxanthin is 1000 times higher than that of vitamin E, and the substance is used in the food industry as a food additive, for wellness products and food which promotes health, it is used for instance in products for strengthening eyesight. In the wild, the algae, or rather the pigment is responsible for the red color of crustacean and salmon.

Breakthrough achieved with the decanter

The biotechnology company had already tested numerous technologies in order to achieve the high astaxanthin figures with the separation of the flagellates; the breakthrough was achieved with trials at the GEA test center in Oelde. The still extremely low density difference as well as the small size difference still posed problems, and this is the reason why it was not possible for a standard decanter to be used. However, the classifying process was successful with a special improvement made to the method of operation of the test decanter.


Spectacular red

Biotechnology companies cultivate Haematococcus, a green alga, in order to produce the red pigment astaxanthin. Under conditions of stress, such as a shortage of food and more intense UV radiation, the green algae produce a permanent and intensive red pigment, namely astaxanthin, for protection. During the industrial production of haematococcus, the algae also go through a natural aging process. The young algae, namely the flagellate, are mobile, green and on average measure only 5 micrometers; they then turn into adult algae, Palmella, with a diameter of 20 to 50 micrometers. If these algae, which are still green, are exposed to stress and UV radiation in a photo-bio reactor, they form a red cyst, namely akinate. This is the product which interests the manufacturer. But it’s extremely difficult to harvest the akinate in an efficient manner, until now at least.

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