To leverage the huge potential that microalgae have as both healthy and sustainable food and feed, we still need to improve some steps across the value chain. The drying process is one of them: after microalgae are harvested, it is a crucial step to ensure a safe and long-lasting product.

Conventional drying methods, such as freeze or spray drying, are energy and time consuming. In a previous blog post, ProFuture partners have already explained the difference between freeze drying and solar drying: while the lower energy consumption of solar drying was a clear advantage, they were not yet sure how the nutritional value could be kept at the same quality. Now, new results are available in the latest paper Drying Microalgae Using an Industrial Solar Dryer: A Biomass Quality Assessment, published by ProFuture partners Necton, German Institute of Food Technologies (DIL e.V.), Centre of Marine Sciences (CCMAR), GreenCoLab and Flanders Research Institute for Agriculture, Fisheries and Food (ILVO).

An interview with Alexandre Rodrigues and Benjamin Schmid, ProFuture partners at Necton in Portugal, gives interesting insights into the study and the cultivation and commercialisation of microalgae.

What were the results of your study on solar drying?

We found that industrial solar drying is a sustainable technology that also has a huge potential to preserve high-quality microalgal biomass for various markets at lower costs. Our study tested an indirect and hybrid solar dryer as an alternative to conventional freeze drying of industrially produced Tetraselmis chui and Nannochloropsis oceanica wet paste.

We assessed the effects on biomass quality parameters, including biochemical profiles, functional properties, and microbial safety and could see some interesting results:

• No significant differences were found between the applied drying technologies for total proteins, carbohydrates, lipids, and fatty acid profiles.
• Some pigments showed significant differences, with Chlorophylls displaying up to 44.5% lower contents in solar-dried samples.
• Minor differences were registered in the mineral profiles (<10%).
• Analyses of microbial safety and functional properties of the solar-dried biomass appear adequate for food and feed products.

What do the findings presented in the paper mean for the food industry?

The analyses of functional properties and microbiology of solar-dried microalgal biomass revealed that it has interesting properties and can be considered food safe. This suggests that solar drying is a promising technology to provide high-quality biomass for food and feed markets. Moreover, further studies have shown that the drying process is more sustainable, spending less electrical energy than freeze drying.

What was the most interesting result for you?

The analysed quality parameters showed no significant differences between solar- and freeze-dried biomass except for some pigments and minerals. Given the fact that solar drying is more sustainable, this was a very promising result. In fact, additional experiments have shown that the applied solar dryer can be up to 10-fold less energy-demanding than the freeze dryer.

How did ProFuture partners work together on this study?

Necton was responsible for planning the study (together with GreenCoLab) and drying the biomass with the two technologies. Proximate composition, pigment, and fatty acid profile analyses were carried out at GreenCoLab (Associação Oceano Verde, Faro, Portugal). The German Institute of Food Technologies (DIL e.V.; Quakenbrück, Germany) analysed mineral element contents, while the Flanders Research Institute for Agriculture, Fisheries and Food (ILVO; Melle, Belgium) determined functional properties and microbial safety.

What are the next steps?

Techno-economical assessments; upscaling; solar drying of other microalgal species.

Can you introduce the team at Necton/Phytobloom?

Established in 1997, Necton is the oldest company in Europe that specialises in the cultivation and commercialisation of microalgae. The company was set on an ideal location to grow these microorganisms in the natural park of Ria Formosa on the sunny south coast of Portugal.

Throughout the years, the company acquired extensive knowledge in cultivating marine, freshwater, and hypersaline species. To produce the microalgae biomass the facility relies on more than 100 m3 of horizontal tubular photobioreactors and a 200-m3 raceway pond. Necton’s growth is supported by a continuous R&D effort that includes participating and managing several national and European-funded research projects. Through this effort, Necton was able to achieve scientific, technological and market knowledge of microalgae cultivation and applications for the aquaculture and cosmetic sectors, among others. The company’s history, experience and constant collaboration with universities, research organisations and other companies have made Necton one of the leading European companies in microalgae biotechnology.