Effect of processing on functional properties of Spirulina protein preparations

The present investigation has been undertaken selecting a protein rich blue green alga Spirulina platensis in relation to change in functional properties of its proteins on chemical treatment with succinic anhydride, acetic anhydride and formaldehyde for succinylation, acetylation and methylation respectively. Modified proteins have been studied for their functional properties such as protein solubility, foaming properties; emulsification properties and viscosity. Protein solubility in unmodified water soluble Spirulina protein fraction was found to be 23%. It decreased considerably on treatment with all the three modifying reagents. Emulsification activity (EA) increased slightly on methylation, whereas succinylation and acetylation resulted in a decreased EA and emulsion stability (ES). Foam capacity (FC) increased on treatment with succinic anhydride at all the concentrations used, whereas acetylation and methylation could show an increase in FC only at lower concentrations. FC was found to be maximum on succinylation and minimum on acetylation. Foam Stability (FS) was found to be much higher with methylation and acetylation. The protein fraction modified with succinic anhydride has shown the maximum viscosity followed by acetylation. Methylation however, caused a rapid decrease in viscosity and it was more pronounced at lower concentrations.