Spirulina microalgae: the new functional food option in our diet

Microalgae have turned out to be a potential alternative to the use of synthetic sources for these ingredients. Spirulina is a type of microalgae that has been consumed by humans since the times of pre-Columbian America, and it naturally produces antioxidants (like carotenoids and Xanthophylls), and antimicrobial compounds like polysaccharides or fatty acids among other beneficial substances.

The extraction process using supercritical fluids, (supercritical fluids are any substance above certain set pressure and temperature conditions known as their critical point, that grants them physical properties in between those of liquids and gases) has taken shape in the last few years as an alternative to the classic extraction means. It shortens the extraction times and does not require the use of organic solvents that damage health and the environment. The most common supercritical fluid used is carbon dioxide, because of its zero toxicity, versatility, price and relatively soft critical conditions (73 bar, 31 ºC), besides these advantages, being a gas at room temperature, it does not leave residue in the extracted substance.

The work carried out by the associated unit for food science Universidad Autónoma de Madrid –Consejo Superior de Investigaciones Científicas consisted in the development of an extraction method using supercritical CO2 and the posterior analysis of the obtained substance by in vitro methods to evaluate its antioxidant and antimicrobial capabilities. Then a chemical analysis of the extract was carried out using chromatographical techniques in order to correlate the activity of the substance to its chemical composition.

The results show that the Spirulina microalgae could be a good source of functional food ingredients with antioxidant action thanks to the presence of carotenoids deriving from chlorophyll, and bacterial growth inhibiting action thanks to certain fatty acids. In optimal extraction conditions (220 bar y 55 ºC) an extract can be obtained with both a high activity as an antioxidant and antimicrobial action, thanks to the combined method of extraction-fractionation developed by this research group.