High protein ingredients of microalgal origin: Obtainment and functional properties

Protein concentrates and isolates were developed from the microalga Spirulina sp. LEB 18 biomass and characterized by functional aspects for food application. Proteins were solubilized at pH 11 and precipitated at pH 4.2 (protein isoelectric point determined by potentiometric titration), with the aid of a high-speed homogenizer. With this procedure, it was possible to obtain a protein concentrate with 83.9 ± 1.7 wt% of protein and a protein isolate with 91.3 ± 1.2 wt%. Protein extraction from this microalga allowed a significant increase in protein solubility and foam stability. Furthermore, proteins from both concentrate and isolate presented higher resistance to thermal denaturation than the original proteins of Spirulina sp. LEB 18 biomass. These results show the application potential of the concentrate and the protein isolate from Spirulina sp. LEB 18 in foods for protein supplementation, since they have >80 and 90% protein, respectively. Using proteins from microalgal sources can serve as a sustainable alternative to meet world food demand. The isoelectric precipitation extraction method can be applied on a large scale, achieving high yields. Protein extracts present potential application in specific foods for protein supplementation. Protein extraction can be allied to other biocomposites extraction, such as carbohydrates and lipids for biofuels production.