Methods for preparing products containing moisture-sensitive materials, including biological materials such as proteins, peptides or live cells, comprising at least the steps: (i) providing a coating liquid comprising at least one active, a sugar polymer and a water soluble/miscible solvent; (ii) providing a quantity of microparticles comprising at least water soluble gel forming solid particles; (iii) fluidizing said quantity of microparticles within a processing chamber of a of a suitable apparatus to form a fluidized bed of said microparticles; (iv) spraying said coating liquid onto said fluidized bed from beneath the fluidized bed to coat said microparticles therewith under saturated moisture conditions; and (vi) allowing coated microparticles to dry, are described. Also described are compositions and uses.