chemical biological agents to be encapsulated are blended into an aqueous dispersion of an unmodified starch comprising about 5 % to about 25 % by weight amylose . the dispersion , having an initial starch solids content of about 20 % by weight , is characterized by completely disrupted starch granules and completely disassociated amylose molecules that are not significantly depolymerized . subsequent drying is accomplished by reassociation of the amylose molecules which converts the dispersion into a protective matrix and binds the agents within the interstices of the reassociating starch chains . rate of release of agents to the environment can be altered by varying the proportion of amylose in the starch . encapsulation of biologically active compositions provides protection against degradative environmental conditions , improves safety in handling , and slows the release of such compounds to the surrounding medium .