Microalgae are considered the food/feed of the future for the many nutrients they contain: proteins, lipids, carbohydrates and vitamins. However, these nutrients are trapped inside the microalgae cells, often protected by a tough cell wall. For these nutrients to be used in food and feed production, they must first be efficiently extracted from inside the cells.

There are many techniques to extract internal compounds from cells – from chemical extraction to mechanical disruption – and they vary in terms of efficiency, productivity, financial costs, scalability and environmental impact.

In ProFuture, researchers are analysing and comparing how different extraction techniques affect the quality and the quantity of the proteins obtained from microalgae. The goal is to find which methods are most suited for the large-scale production of microalgae, while being cost-efficient and with a relatively low environmental footprint (in particular concerning the energy consumption).

One of such methods is the bead milling - a well-known technique used industrially in ceramic, pharmaceutical, paint, paper and cosmetic industries, now also used in biotechnology to destroy cells. The system consists of an agitated chamber filled with ceramic beads with a size usually between 0,3 to 2 mm. The collisions between beads break the cells that are between them and allow the nutrients to come out of the cells to the extract liquid. The disrupted cells are then separated from the liquid extract containing the nutrients by a solid/liquid separation technique.

Currently, ProFuture researchers in AlgoSource conducting trials to understand the optimal conditions in which microalgal proteins can be recovered from the liquid phase after bead milling of the cells.

The bead milling technique allows a good productivity, with more than 90% of Tetraselmis cells destroyed within 3 minutes, and is well reproducible between experiments. However, some challenges remain such as the low microalgal protein extractability and the coupling with the next unit operations.

The next step include further purification, to increase the purity of the proteins and their functionality for food and feed applications.

Stay tuned for more ProFuture news!