Protein extraction from microalgae residue and nutritional assessment.

On the basis of determining isoelectric point of algae residue protein obtained from Scenedesmus dimorphus, this study investigated the effects of pH values, ratio of liquid to solid, extraction temperature and time on protein extraction rates, and assessed the nutritional value of protein extracted from microalgae residues. The results from orthogonal experiments revealed the optimum conditions for extracting proteins from algal residues (pH: 12; liquid-to-solid ratio: 40 mL/g; extraction temperature: 45 ℃; extraction time: 140 min). It was observed that under the optimal conditions, the protein extraction rate was 40.13%. Essential amino acids account for 44.3% of the proteins obtained from algal residues. The content of anti-nutritional factors in algal residues was significantly reduced, and the digestibility of algal residue proteins was higher than the digestibility of algal powder. This indicated that algal residues could be an ideal source of proteins for humans.