The Sulfated Polysaccharide from Red Microalgae as a Hydrocolloid for the Food Industry

In the food industry, there is an ongoing search for novel – particularly bioactive – ingredients to enhance and extend the functionality of emulsions. While most hydrocolloids can act as stabilizers of oil-in-water emulsions, only a few are suitable as emulsifiers. A promising candidate as a novel hydrocolloid emulsifier is the sulfated polysaccharide produced by the cells of red microalgae. The unique rheological properties of this hydrocolloid confer the substantial surface activity necessary to facilitate the formation and stabilization of fine droplets during and after emulsification. The aim of this study was to evaluate the effect of the microalgal polysaccharide on emulsion functionality, as compared to λ-carrageenan, an emulsifier commonly used in the food industry. Stable emulsions were obtained after a short homogenization (3 min) of the oil and water phases with the microalgal polysaccharide, while λ-carrageenan emulsions showed signs of creaming. The microalgal polysaccharide was more effective in stabilizing larger oil droplets. In addition, the creaming velocity and droplet size of the polysaccharide emulsions were barely affected by the addition (0‑150 mM) or removal of NaCl to/from the medium, extreme pH values (3-9) or even the degradation of the polysaccharide by sonication. Under the same conditions, λ-carrageenan emulsions separated into two phases, and droplet size increased. The algal polysaccharide emulsions remained stable – under a variety of conditions – for long periods of time (up to months), which is a particularly valuable quality for the food industry. These findings illustrate the potential of the microalgal sulfated polysaccharide as an emulsifier and bioactive agent for the food industry.