Modification techno-functional properties of spirulina protein concentrates (Arthrospira Platensis) as O/W emulsifier by conjugation and electrostatic complexations

Spirulina (Arthrospira platensis) is an intriguing but underutilized protein source in the food industry. This study aims to investigate the effect of electrostatic complexation and conjugation on the techno-functional properties of the protein spirulina and its benefits as an emulsifier in oil-in-water (O/W) emulsion in order to broaden its application as food ingridients. The Spirulina protein concentrate (SPC) interacted with carrageenan via electrostatic and conjugation (Maillard reactions). The properties of the complexes and conjugates were then evaluated. The results showed that the turbidity, browning index, and thermal stability of the solution were influenced by the protein: polysaccharides ratios and pH conditions. The best conjugates (MR) were obtained at a ratio of 2:1 with a pH of 7.0 based on confirmation of the degree of glycation, browning index value, emulsion activity index (EAI) value, and emulsion stability index (ESI). The best electrostatic complexes (EI) were obtained at a ratio of 2:1 with a pH of 2. SPC-carrageenan conjugates and complexes exhibited different functional properties based on conformation structure by FTIR and thermal properties by DSC. Conjugation and Electrostatic Interaction increased the denaturation temperature of SPC, which were reflected in the emulsions stabilized by maillard reaction (MR), electrostatic interaction (EI), and simple mixed (SM) SPC-carrageenan. The emulsion stabilized by MR had smaller droplet sizes, was more evenly distributed, and had better stability towards heating than those stabilized by Native SPC, SM, and EI. This study provides valuable basic information for the development of spirulina protein as a green emulsifier and other type of novel food.