Protein extracts from microalgae and cyanobacteria biomass. Techno-functional properties and bioactivity: A review

Abstract

Microalgae and cyanobacteria are photosynthetic and unicellular organisms that contain considerable amounts of proteins, lipids, carbohydrates, and polyunsaturated fatty acids, among others, with applications in the cosmetic, pharmaceutical, and food industries. These microorganisms can accumulate protein up to 70 % of total biomass depending on the microalgal strain, hence they have been regarded as an alternative protein source for the future. Microalgal proteins have important applications such as emulsifying, foaming, and gelation properties, which are important for the determination of quality and texture of foods. Some microalgal peptides possess important bioactivity with many health-benefit effects. Therefore, to maximize the production of proteins from microalgae and cyanobacteria, many protein extraction procedures have been studied to increase the economic return. They have been tested towards higher protein yields at low energy cost, the preservation of protein native properties, and lower cell debris. This later is fundamental to facilitate the subsequent purification processes so that the overall cost can be reduced. The aim of this work is to review some cell disruption processes for the extraction of protein from microalgae and cyanobacteria, considering that this step is crucial for the overall process due to the high rigidness of microalgal cell covering, which can hamper the release of proteins. It also aims at reviewing the purification techniques after cellular disruption, from conventional to more recent approaches, and finally addresses the antioxidant, antidiabetic, antihypertensive, antibacterial and other bioactive properties of microalgal protein hydrolysates and peptides.