A sticky substance may indicate generally some residual solvent, but ginger has lots of oil that can be extracted by alcohol. In essence, you may not get a powder form of ginger extracted by organic solvents. If you want to make sure that all the water from the extract is removed for accurate dosing in animal experiments, freeze drying is the best. Put the extract in a freeze dryer and your extract no matter sticky does not matter as it is what we expect to see.

Dear Zainab,

I agree with Solomon in that your sticky material may still contain some residual solvent. Moreover, such plant extracts are always mixtures of compounds which show no tendency to crystallize. One easy way to possibly convert your sticky material into a solid is to triturate it with diethyl ether. Just add some diethyl ether and stir the mixture vigorously with a glass rod. Chances are that a solid will form. There is no guarantee, but it's worth a try.

Good luck with your work!