Hydrocolloids from the Freshwater Microalgae, Palmella texensis and Cosmarium turpinii

The extracellular polysaccharides of two freshwater microalgae were examined as potential sources of hydrocolloids. A 0.10% solution of polysaccharide from Cosmarium turpinii (UTEX LB 1042) was pseudoplastic and more viscous than other selected hydrocolloids, indicating an ability to function as a thickening agent. The polysaccharide from Palmella texensis (UTEX 1708) produced low‐viscosity solutions and showed good pH (3.5 to 9.5) and temperature (20°C to 80°C) stability. A 1.00% solution of P. texensis polysaccharide showed Newtonian‐like flow properties at low shear rate (2.25 sec ‐1 to 45 sec ‐1 ). Fucose, xylose, galactose, glucose and glucuronic acid were found from the C. turpinii polysaccharide, and only galactose was identified from the P. texensis polysaccharide.