The invention relates to a compound, comprisinga) a first starch derivative selected from the group consisting of hydroxyalkyl starch, carboxyl alkyl starch, ester starch and arbitrary mixtures thereof, wherein the starch derivative has a mean relative molar mass Mw1 and a degree of molar substitution MS1, andb) a second starch derivative selected from the group consisting of hydroxyalkyl starch, carboxyl alkyl starch, ester starch and arbitrary mixtures thereof, having a mean relative molar mass Mw2 and a degree of molar substitution MS2, characterized in that Mw1 is greater than Mw2 (Mw1>Mw2) and MS2 is greater than MS1 (MS2>MS1).
