Abstract: The preparation and the use of pulverulent compositions consisting of (a) from 10 to 90% by weight of cellulose, (b) from 5 to 60% by weight of an alkali metal caseinate, and (c) from 5 to 85% by weight of a polymer c1) an N-vinyllactam polymer obtained by copolymerization of from 90 to 99.5% by weight of one or more N-vinyllactam monomers and from 0.5 to 10% by weight of a crosslinking monomer, or c2) a polymer obtained by copolymerization of from 50 to 99.5% by weight of at least one vinyl heterocyclyl monomer having a PKa of at least 3.8, from 0 to 49.5% by weight of another copolymerizable monomer and from 0.5 to 10% by weight of a crosslinking monomer, or c3) a mixture of the polymers c1) and c2). The compositions are used in the treatment of biological liquids of plant origin in an unfermented or partially or completely fermented state for sensory stabilization of the liquids with a view to preserving taste and color.