The functional properties of the Porphyridium cruentum, Nannochloropsis spp. and Phaeodactylum tricornutum defatted microalgal biomasses were investigated and compared with those of soybean flour. The following properties were evaluated for each microalgal biomass: nitrogen solubility, water and oil absorption capacities, emulsification capacity, viscosity, and sensory evaluation of spaghettis partially containing microalgal biomass. The results showed that P. cruentum and Ph. tricornutum biomass had comparable functional properties to those of soybean flour. Some functional properties, such as water absorption capacity, show a different behavior than that of traditional flours, due to the high percentage of exopolysaccharides that the microalgal biomass shows, especially P. cruentum biomass. (C) 2004 Elsevier Ltd. All rights reserved.