Feature Article: Process expertise for oil production from microalgae

Oil from microalgae is also categorized as a novel food. It comes from cultivated microalgae such as Ulkenia or Schizochytrium. The oil contains the long-chain omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are directly available to the body, can be easily utilized and therefore are especially valuable.

The essential omega-3 fatty acids DHA and EPA otherwise only are found in fatty marine fish such as salmon, sardines or mackerel. Plant oils such as canola, flaxseed and walnut oil, on the other hand, contain only their precursors, alpha-linoleic acids, from which the human body can synthesize only small quantities of DHA and EPA. As alternative sources, algal oils are therefore particularly valuable to people with vegan or vegetarian diets or who do not want to consume fish for environmental reasons.

Food producers wishing to focus on biotechnology production methods such as precision fermentation or the cultivation of microalgae for oil extraction face a range of challenges. How can efficient production be achieved in a complex, precisely regulated system like the bioreactor? It certainly demands a lot of process expertise — and this is exactly what ZETA can contribute as an experienced partner!

Joint Venture with Bühler

Competence and expertise were combined in a joint venture with the Swiss technology company, Bühler. The new company, Eridia, will develop food and animal feed biotechnology systems, most notably in the areas of precision fermentation and cellular agriculture.

A Swiss food company put its trust into ZETA’s expertise and commissioned a design concept for a bioreactor. The working volume of the tank should be an ambitious 130 m³ to allow large scale microalgae cultivation for oil extraction. Media supply and connection were also part of the concept study.

Challenge - size of the container

As with all biotechnology production processes, the aim was to achieve optimal conditions for growth. One of the challenges here was the size of the tank because scaling effects come strongly into play here. The water column in the tank is over 10 meters high. This influences the size of the air bubbles to be distributed, for example, and further important process parameters.

The concept study included proposal of a suitable tank geometry, in addition to development of a standard agitator with a special design to avoid shear forces and a sparger for aeration. There was special emphasis placed on hygienic issues, such as the cleanability of the system. The customer received a conceptual flowchart and a media list, as well as a standard document for the tank specification. Furthermore, ZETA provided support for determining the optimal aeration rate and agitator speed.

Focus on process safety

Ensuring the aseptic process and all quality-related product parameters is always the focus of engineering at ZETA. Food safety and hygienic design have the highest priority.