Microalgae, where do we stand?

“There are more algae in the oceans than stars in all the galaxies in the universe”
Ruth Kassinger

Microalgae have been part of the human diet for thousands of years, archeological records report that they have been around for more than a billion years. Aztecs were already harvesting spirulina from lakes in Mexico or consuming a blue-green cake made from a type of microalgae called Arthorspira. However, it has only been recently that there has been a growing interest in them from the food industry. 

Microalgae are microscopic unicellular algae, which consist of separate cells, sometimes grouped in little clumps or chains and others invisible to the naked eye. They are considered one of the foods of the future for their unique nutritional and environmental properties.

Health

Research has shown their ability to meet some dietary needs of the growing population. Algae are a rich source of Omega-3 fatty acids. Actually, fish get those compounds from algae, so why not get them directly from the natural source? Omega-3 ω3-LC-PUFA is essential for brain development for children and brain health for adults, having an impact for example on memory function. and are really useful to prevent cardiovascular diseases and brain disorders, such as Alzheimer’s 

They are also a great source of protein, dietary fiber, and bioactive compounds with certain health benefits. For example, spirulina contains 63% protein in comparison with soy, the most used plant-based protein source which contains 40% protein. Due to the nutritional composition, some microalgae have been used for decades as supplements for the food industry. However, they are becoming more relevant because they present a great alternative to produce vegan protein alternatives and as a natural source of protein to produce food products for different sectors, and not just to be used as supplements. Promising food applications due to their nutritional properties: as part of dairy products since Chlorella already has been successfully incorporated in different yogurts and cheeses and some authors discussed that some species such as Arthrospira spp. can “stimulate” the growth of bacteria. Another promising application seems to be in cookies and biscuits as a coloring agent and as a potential antioxidant and nutritional added value. Moreover, they are very versatile and can be obtained in different formats such as powder, oils, or paste.

Sustainability

Microalgae are considered one of the most sustainable sources of food ingredients. Microalgae are generally photoautotrophic which means that, in their natural environment, they convert CO2 and light into oxygen, helping to reduce the carbon footprint. They are efficient in the purification of wastewater and removal of greenhouse emissions.  

Cultivation

Microalgae are easy to cultivate, can produce large amounts of biomass, and need very few resources and fertilizers. Many of the companies currently cultivating microalgae use fermentation tanks (photobioreactors) with the aim of obtaining abundant biomass yield. They add traditional yeast to activate the fermentation and then the culture is injected in large photobioreactors where they grow until they reach a certain quality. Then the microalgae are harvested and processed. It represents a sustainable way of cultivating microalgae which minimize agricultural land use and helps with carbon dioxide fixation. According to an article by the BBC, in their natural environment, microalgae is net carbon negative since the process removes carbon from the atmosphere. Microalgae are also considered one of the most sustainable sources of food because they can be grown in specialized facilities almost anywhere and therefore do not compete with other crops for arable land. 

Types of microalgae

There are between 200,000 and 800,000 varieties of algae. Even though 70% of the production is based on chlorella and spirulina there is a huge kingdom of microalgae. There are microalgae that are white, yellow, or turquoise and there is an infinite world of possibilities. The species that have commercial importance would include Haematococcus, Dunaliella, Botryococcus, Phaeodactylum, Porphyridium, Chaetoceros, Crypthecodinium, Isochrysis, Nannochloris, Nitzschia, Schizochytrium, Tetraselmis, and Skeletonema. Regarding their protein profile, Chlorella and Arthrospira have a well-balanced amino acid profile according to WHO regarding human requirements. On the other hand, Arthrospira, Chlorella, and Nannochloropsis are good sources of oligosaccharides. As you can see, there are different types of microalgae with slightly different nutritional properties, and we should not just focus our attention on spirulina and chlorella.

Organoleptic properties

Recent research articles highlight that, organoleptic properties when introducing microalgae in the market are of key importance for food product development since they really affect the consumers’ acceptance of a product and the purchase intention. 

Color

Natural colorants and dyes are getting more attention over synthetic alternatives due to increased awareness from the consumer regarding health and sustainability. Microalgae produce various pigments such as chlorophylls (green), carotenoids (yellow, orange, and red), or phycoerythrin (red) that have the capacity to be explored and exploited as a source of natural intense colorants. 

Texture

Besides their nutritional compounds, microalgae contain as well different structural biopolymers such as polysaccharides or proteins with texturizing capacity. Some species can provide techno-functional properties such as emulsifying, gelation, water absorption, and foaming properties. Some authors have shown that they could act as fat replacers and mimic fat in different plant-based food products. However, they need to be used using the right processing operations and intensity. 

Flavor

Microalgae can work as a potential plant-based seafood flavoring because of their aromatic profile. Depending on the type of microalgae and dosage they will have slightly different aromatic profiles but in general, they possess a high umami taste and fishy and salty flavor. Some aroma compounds that have been identified in microalgae would include some seafood aroma compounds such as dimethylsulfide, fatty acids-derived compounds, trimethylamine, and some taste compounds such as glutamic acid.

Legislation

European legislation considers microalgae as “novel foods”. According to the regulation, “new” foods are those foods that were not sold in the EU before 15 ay 1997 and would need to provide evidence that they are safe to eat. All the microalgae, except chlorella and spirulina, are considered “new” and therefore must undergo long procedures to prove that they meet the food safety regulation standards.

Even though microalgae consumption is not widespread yet and there is a lack of large-economy scale and processing, they seem to be a great alternative for the future of food. With a food system simply unsustainable, humans need to find alternative sources of protein.