Pilot-Scale Production of A. platensis: Protein Isolation Following an Ultrasound-Assisted Strategy and Assessment of Techno-functional Properties

The aim of the present study was to produce Arthrospira platensis (BEA 005B), commercially known as Spirulina, using commercial fertilisers as the nutrient sources and to use the produced biomass as a feedstock for isolating of proteins with improved functionality. This microalgal strain was not studied before. A culture medium formulated using commercial-grade fertilisers resulted in biomass and protein productivities comparable to those of a standard medium. The biomass was produced using pilot-scale photobioreactors. Ultrasound-assisted isoelectric solubilisation/precipitation enabled us to recover approximately 86.3% of the proteins from A. platensis , obtaining extracts of high purity (90–95%) and a high content of essential amino acids. The solubility, foaming, emulsifying and gelling properties were pH dependent. Improved functionality was observed at pH values far from the isoelectric pH, which in this case was 3.9. The highest solubility was obtained at a pH = 10, while the foaming (182.3%) and emulsifying (80.6%) capacities were higher, at pH values of 2.0 and 6.0, respectively. The lowest concentration required to form a gel was 60 g·L −1 at a pH = 6.0. The amino acid profile and the functionality of the isolated proteins, which compared well with those of soya, suggested the potential of A. platensis –derived proteins for being used in the development of novel foods.