A novel study conducted by the Technical University of Denmark's (DTU) National Food Institute has found the best conditions in which to cultivate the microalgae Nannochloropsis oceanica.
The organism, which is naturally rich in key health-supporting nutrients such as protein, vitamin K2 and omega-3 fatty acids like EPA, shows significant potential as a functional food ingredient; however, depending on the conditions its grown in, microalgal colonies can vary in nutritional value.
Therefore, researchers set out to determine how key factors such as light, temperature and salinity affect the bioavailability and quality of N. oceanica as a functional ingredient, and how producers of the superfood should approach its cultivation.
Approaching research from a new angle
Although there has been previous research into how Nannochloropsis oceanica grows, as well as what drives fatty acid production, the DTU wanted to approach it from a different angle "we chose to compare these factors with the simultaneous production of proteins and vitamin K2," noted PhD and lead of this study's cultivation experiments, Emil Gundersen.
"By achieving this, we would provide a more comprehensive overview of the intricacies of the cultivation phase, which allows ingredient producers to achieve the most nutrient-rich biomass."
To look into the optimal conditions for the production of EPA, vitamin K2 and protein, the team at the DTU used response surface methodology to test growth between the ranges of 19–27 °C, 120–360 µmol·m−2·s−1 and 2.3–3.7% for temperature, light intensity and salinity, respectively.
The two-step process as the key to nutrient-rich yield
Through Emil's cultivation experiments, the team at DTU observed that "if temperature and light intensity is high, Nannochloropsis oceanica grows quickly and produces large amounts of protein."
"However, the concentration of omega-3 fatty acids and vitamin K2 is higher when the temperature is lowered," stated Gundersen.
"The research suggests that the best results will stem from the initial cultivation at high temperatures under strong light, which will trigger increased growth and protein production. The temperature should then be lowered, which allows the microalgae to focus on producing key nutrients."
It should be noted that this cultivation study was not conducted on a large scale, so further testing to confirm this would be highly beneficial.
"Temperature regulation is a well-known concept in the current fermentation industry. Therefore, we believe it will be relatively easy to implement a two-stage process based on temperature in future commercial production of microalgae," said Emil.
A plant-based vitamin K2 solution
Vitamin K2 is a highly important dietary nutrient, being responsible for effective blood clotting and calcium transportation, as well as impacting cardiovascular, bone and brain health.
However, most vitamin K2 is obtained from animal-based foods, which can make it tricky for an individual on a plant-based diet to obtain enough K2 in their diet.
"It is interesting that microalgae could potentially serve as a source for producing vitamins like K2, which we usually obtain from animal sources, in a vegan way," noted Gundersen.
"The next step for us will be to investigate how the bioavailability of the proteins, omega-3 fatty acids and vitamins can be increased in microalga strains. This is necessary as they have a thick cell wall that is difficult for the human digestive system to break down," he concluded.
Reference
1 https://www.mdpi.com/1660-3397/22/11/505