Abstract: A process for producing microparticles, in which an aqueous solution of purified amylopectin-based starch of reduced molecular weight is prepared, the solution is combined with biologically active substance, an emulsion of starch droplets is formed in an outer phase of polymer solution, the starch droplets are made to gel, the gelled starch particles are dried, and a release-controlling shell is optionally applied to the particles, wherein at least one buffer substance having the ability of keeping the pH of the produced microparticles above 3 if exposing the microparticles to an aqueous evironment is added at any stage during the process. Microparticles which essentially consist of said starch, have an amino acid content of less than 50 ?g and have no covalent chemical cross-linking and which have the aktivity of keeping the pH above 3 if exposed to a aqueous environment.

Abstract: A process for producing microparticles, in which an aqueous solution of purified amylopectin-based starch of reduced molecular weight is prepared, the solution is combined with biologically active substance, an emulsion of starch droplets is formed in an outer phase of polymer solution, the starch droplets are made to gel, the gelled starch particles are dried, and a release-controlling shell is optionally applied to the particles, wherein at least one buffer substance having the ability of keeping the pH of the produced microparticles above 3 if exposing the microparticles to an aqueous evironment is added at any stage during the process.

Abstract: A vaccine composition which comprises an immnunologically active substance embedded in microparticles essentially consisting of starch having an amylopectin content exceeding 85% by weight, of which at least 80% by weight has an average molecular weight within the range of 10-10000 kDa, and without any covalent chemical cross-linking between the starch molecules.