Influence of protein concentrations and protein to alginate ratios on characteristics and qualities of spirulina protein-spherification

A leftover product called spirulina residue is a by-product generated from phycocyanin extraction. This by-product is rich in protein, containing approximately 30-40% of protein, which offers the potential opportunity for value-added production and effective utilization. A nutritious spirulina protein was successfully prepared from the by-product in our previous work. In this work, the potential use of spirulina protein extracts for non-meat-based food applications was explored in the form of spirulina protein nutritious beads. The amino acid profile of the resulting spirulina protein was also examined. The major aim of this study was to investigate the effects of the concentration of spirulina protein and spirulina protein-to-alginate ratio on the characteristics and qualities of spirulina protein spherification. Two concentrations of spirulina protein, namely 5% and 10% (w/w), were employed, while the concentration of alginate solution was fixed at 2% (w/w). The spirulina protein-to-alginate volume ratio was tested at  1/1, 3/1, and 9/1. The spherification process was carried out in a 2.5% calcium chloride solution. The results showed that the spirulina protein extracts contained all the essential amino acids (EAA) with a high EAA ratio, accounting for 36.5% of total amino acids. Furthermore, the study exhibited that the sphericity of spirulina protein beads, prepared using 10% protein concentration at the spirulina protein-to-alginate ratios of 1/1 and 3/1, were not significantly different and were in a range of 1.02-1.05. The results of the texture analysis showed that the spirulina protein beads prepared at the ratio of 1/1 were harder than those at the 3/1 ratio. Sensorial results indicated that the spirulina protein beads prepared at the ratio of 1/1 received the highest acceptance scores of 6.95+1.43 which meant that it was liked slightly to moderately. The findings suggest that spirulina protein extracts could be a promising alternative protein ingredient for nutritious protein diet applications.