Disclosed is a method for thermal permeabilization of the biomass of microalgae of the Chlorella genus in such a way as to recover therefrom the soluble fractions which are enriched in particular with proteins and with oligosaccharides, including the following steps: provision of a microalgae biomass heat treatment in steps at a temperature of between 60 and 130° C., preferably 60 and 90° C., for 1 to 5 minutes cooling to a temperature of between 0° and 10° C. and recovery, concentration and enrichment of the soluble fractions from which the microalgae cells have been removed.
