PhD defence by Emil Gundersen

Principal supervisor:

• Professor Charlotte Jacobsen

Co-supervisors:

• Senior Researcher Jette Jakobsen
• Associate Professor Susan L. Holdt

Examiners:

• Professor Solange I. Mussatto, DTU Bioengineering
• Professor Rene H. Wijffels, Wageningen University & Research
• Associate Professor Niels-Ulrik Frigaard, University of Copenhagen

Chairperson at defence:

• Associate Professor Ditte B. Hermund

Resume
As the world population continues to expand, so will the global demand for food production, especially foods rich in protein. To stay within the limits of what our planet’s ecosystems and resources can handle, this future production must be mainly plant-based. However, the scarcity of certain nutrients such as long chain omega-3 fatty acids and vitamin D in plants poses a nutritional challenge. This calls for a need to explore and develop new, non-animal sources of nutrients, such as microalgae.

In this PhD project, we sought to advance the development of the microalga Nannochloropsis oceanica as a potential food ingredient by addressing key bottlenecks in its production and nutritional quality with a focus on protein, omega-3 fatty acids, and vitamins K and D. Multiple cultivation experiments demonstrated that nutrient-rich side streams from industrial enzyme production could partially replace synthetic fertilizer used during cultivation. These experiments further demonstrated that cultivation conditions, especially light intensity and temperature, could be used to fine-tune biomass production and quality. Under optimal conditions biomass containing around 50% protein, 4% long chain omega-3, and high levels of vitamin K2 was produced. Exposing the microalgal culture to a brief UVB treatment before harvesting, added a significant amount of vitamin D3 to its already rich nutrient profile. Unfortunately, experiments with the processing technology bead milling failed to increase the digestibility of the final biomass product, making the nutrients hard to exploit in the human body.

In conclusion, this PhD project has provided valuable results and information for the further development of N. oceanica as a potential source of protein, omega-3 fatty acids, and vitamins K and D. With additional processing, the optimized biomass could readily be converted into omega-3- and vitamin D-rich oil and high-protein powder. Specialized products that can provide the rare nutrients needed in the sustainable, plant-based diet of the future.

A copy of the PhD thesis is available for reading at the department.