Scientists describe the advantages and drawbacks of different methods of receiving valuable compounds by microalgae

Scientists at BFU named after Kant Immanuel studied different approaches used for extracting bioactive compounds from microalgae. This identified the advantages and disadvantages of the existing methods: solvent extraction, cold pressing and others. The knowledge gained will help optimize the process of isolating valuable compounds for food, pharmaceutical and cosmetic industries. The study was published in Algal Research journal.

Microalgae is an important source of oxygen in aquatic ecosystem as well as the basis of the diet of small marine and freshwater inhabitants. These organisms also synthesize valuable for humans compounds with anti-inflammatory, anti-viral and anti-tumor properties, meaning polyunsaturated fats, carotenoids, vitamins, antioxidants and others. Extracting these components from algae cells is difficult — it's important not to disrupt the structure of the molecule and retain their biological activity. Therefore, scientists have developed a variety of isolation (extraction) methods; however, each of their advantages and drawbacks still haven't been comprehensively evaluated.

Scientists from Immanuel Kant Baltic Federal University (Kaliningrad) together with colleagues from Borneo Marine Research Institute (Malaysia) and Nanjing Normal University (China) compared several classic methods of extracting beneficial compounds from microalgae.

The most common approach — solvent extraction — is that microalgae cells are placed in organic solvents, such as hexane or ethanol. Those, in turn, penetrate into the cell, bind to target compounds, such as lipids, which yield them. The authors emphasize that this method is highly efficient, yet requires the use of toxic dissolvents that may harm the environment.

Another approach is cold pressing, in which the cells are mechanically destroyed (with a press). Because of the pressure, the necessary for the researchers intracellular contents come out of its cell membranes. Research shows that this method allows to retain temperature-sensitive nutrients, for example vitamins and antioxidants. It is environmentally-friendly, but has low efficiency — by cold pressing, it is possible to extract only a small proportion of the necessary compounds of the total amount contained in the cells.

Steam distillation — a method when the algae is treated with steam at high pressure and temperature, — causes the destruction of cell walls and the release of volatile compounds, oils and carotenoids. Such an approach, just like solvent extraction, is highly efficient, but requires considerable energy and expensive and sophisticated equipment.

A maceration technique is utilized for extracting solid substances such as polysaccharides. Algae cells are ground and insisted in a solvent for an extended period. Maceration is suitable for obtaining temperature-sensitive compounds, but its biggest disadvantage is the duration of the process since this method of extraction may take up to several days.

Having analyzed different methods, the authors concluded that there is no universal approach to extracting valuable substances from microalgae cells. The choice of optimal technology depends on the type of the extracted compounds and the aim of its further use. For example, cold pressing is best suited for extracting oils and solvent extraction would be preferable for extracting lipids used in biofuels.

"Our study summarizes our knowledge about different methods of extracting valuable substances from microalgae cells. These findings will be useful in developing methodologies for creating new functional foods, effective medicines and environmentally friendly biofuels", — says Stanislav Sukhikh, doctor of technical sciences, professor of the Higher School of Living Systems, head of laboratory of microclonal propagation at BFU named after Immanuel Kant.

More information:
Noora Barzkar et al, Conventional extraction methods for bioactive compounds from marine microalgae, Algal Research (2025). DOI: 10.1016/j.algal.2025.104297

Provided by Immanuel Kant Baltic Federal University