The present invention relates to a process for producing proteinmicroparticles in dilute organic acid solutions andin the absence of an alcohol such as ethanol. The microparticles are formed bydissolving a cereal prolamin protein in a concentratedorganic acid solution with agitation and then diluting the solution with anaqueous solution. Protein microparticles havingvacuoles are thus formed. The protein microparticles may be used to formpowders, films, coatings, matrices, scaffolds and thelike. Complete films can be formed from the protein microparticles of theinvention.