Heat-induced gel formation of a protein-rich extract from the microalga Chlorella sorokiniana

Microalgae proteins are an underutilized biomass source for foods with unknown technofunctionalities. Heat-induced gel formation was used in this study to investigate the gelation properties of a protein-rich extract from the microalga Chlorella sorokiniana. Gel formation was achieved at a minimum protein concentration of 9.9 g/100 mL and a temperature of 61 °C was necessary to produce a stable gel network. Small-amplitude oscillatory shear measurements revealed that a weak gel was formed with tan δ > 0.1, which was also evident during backward extrusion measurements. The elasticity of the gels increased when the final Tset was increased and a maximum gel elasticity was obtained at Tset = 80 °C and a heating rate of 1 °C min−1. Increasing the heating rate to 5 and 15 °C min−1 negatively affected the gel strength. Additionally, increasing the ionic-strength and increasing or decreasing the pH negatively affected the gel network, which was related to a change in electrostatic interactions. The results obtained showed that it is possible to produce protein gels from water-soluble protein-rich extracts from Chlorella sorokiniana, which may simplify application of protein extracts from this microalga in foods.