An efficient protein isolation process for use in Limnospira maxima: A biorefinery approach

With an increasing global population, the demand for protein will place unprecedented pressure on protein production worldwide. The full utilization of microalgae biomass as a nutrient source based on the biorefinery concept remains challenging, especially with regard to protein isolation and extraction. Herein, we report a strategy combining sodium hydroxide and urea to extract nearly 85.4 % of the total proteins from the defatted fraction of pellets in a single step, recovering approximately 76.8 % (weight yield) of the total Limnospira maxima biomass through the process. The content of essential amino acids and of total amino acids was 32.1 % and 39.2 %, respectively. Both of them showed high water solubility. When the pH was 7.0, the water solubility of PE-SA and PE-DPA was 88.4 % and 86.2 %, respectively. Moreover, the two end products (PE-SA and PE-DPA) have different characteristics, which might be used in different food formulations. For instance, the PE-SA fraction contains a pigment protein (C-phycocyanin) that may be exploited as a natural blue colorant in functional beverages. Meanwhile, the PE-DPA fraction has a higher protein content, making it a potential protein resource in nutritional supplements or other plant protein-based foods.