Image: © Bodec

Spray drying is a standard method used in the food industry to dry liquid ingredients that are sensitive to high temperatures. This technique is often used for the drying of milk, coffee and spices and it’s also efficient for the drying of microalgae.

Spray drying is characterized by a high evaporation capacity and a low residence time, through the vaporization of the product in a hot air vortex. In other words, it allows to quickly remove water from foods through evaporation by exposing them to heat for only a few seconds. However, spray drying is technique that demands high inputs of electrical energy, which not only can add to the production costs of microalgae-based food products, but also increase their otherwise low footprint.

With sustainability as its core mission, ProFuture is searching for alternative methods that can make the drying of microalgae more sustainable, while still ensuring the high-quality of the end product. While some researchers are assessing the effects of solar drying on microalgae-based ingredients, ILVO is studying the potential of agitated thin film drying (ATFD) as a sustainable drying technique for microalgae.

Agitated Thin Film Drying and current results

In essence, the ATFD is a heated tube under vacuum with a rotor inside to move the material along. This technique uses less energy than spray drying because the water evaporation is speeded up by a vacuum. This also allows the use of lower drying temperatures, which can potentially help better preserve the nutritional and functional properties of microalgae cells.

Image: © Hydrite Chemical Co

In fact, how the ATFD affects the nutritional and functional value of microalgae will be the main criteria used to identify the most suitable drying technique for microalgae single cell proteins.

ProFuture is now conducting studies to understand the effect of ATFD on important nutritional properties of the microalgae, such as their amino acid profile, fatty acid profile, vitamins and antioxidants. It’s also being analysed if there are any changes to their functional properties (solubility, foaming, gelling, interaction with oil and water) after the drying. In fact, the first results on the microalgae Tetraselmis chui and Nannochloropsis oceanica indicated that ATFD positively influences functional properties, resulting in increased foaming, emulsion, water holding and gelling properties.

Soon, the results of these studies combined will provide the necessary insights to identify the most suitable method for drying microalgae protein rich ingredients.

Stay tuned for more ProFuture news!