Performances of Colored Spirulina (Spirulina platensis) Soluble Protein Fractions as Surfactants at Liquid-Liquid Interface

A study was carried out to evaluate the performances of colored spirulina (Spirulina platensis) soluble proteins fractions as surfactants at water/n-dodecane interface using a drop volume tensiometer. Also the mechanical behavior at this interface were studied via an automated drop tensiometer. Various concentrations (0.1%; 0.3% and 0.5% (w/w)) and pH levels (native, 3 and 5) were tested. Results showed that the interfacial tension decay increased with increased protein concentration. Also, at 0.3% (w/w) colored protein in the aqueous phase there were no significant difference in interfacial tension decay between the native pH and the pH3 levels while at pH5 the surface tension decay was greater. The viscoelastic moduli and the equilibrium interfacial tension of the fractions suspensions also decreased with concentration.