Antioxidative Activity and Functional Properties of Enzymatic Protein Hydrolysate of Spirulina platensis

This study aimed to evaluate the effect of enzymatic hydrolysis of Spirulina protein on the solubility, emulsifying activity index (EAI), emulsion stability index (ESI), and DPPH and ABTS radical scavenging activity of extracted peptides. The molecular weight of spirulina protein was determined using the SDS-Page technique. The extracted protein was hydrolyzed by alcalase enzyme and the degree of hydrolysis (DH%) was determined after 2-12 h. Functional properties and antioxidant activities of extracted protein and hydrolyzed proteins were evaluated. The concentration of extracted protein was 108 mg/L and the protein content of Spirulina was 54% (w/w). Most of the protein bands were in the molecular weight range of 15 to 20 kDa, and the DH reached from 4.2 ± 2.1% to 14 ± 1% after 10 h of enzymatic hydrolysis. The lowest solubility was recorded for the extracted protein at pH of 4, and the highest was related to the 14% hydrolyzed protein at pH of 8. Moreover, the extracted protein had higher EAI and ESI than hydrolyzed proteins, and the effect of pH was more evident on the EAI of hydrolyzed proteins compared to ESI. The present study showed that the antioxidant activity of the protein increased with increasing degree of hydrolysis and its concentration. Moreover, the protein with a DH of 14% in all concentrations had the highest inhibition. This work presented that the current method used for extraction and enzymatic hydrolysis of spirulina protein led to the production of peptides that have desirable properties for use in the food industry.