This item has no research benefit, and can be sold freely. This...slurry...of varying genetic material has a considerable nutrient content, and could be used to provide sustenance to the aliens. Unfortunately, this mixture also contains several key markers indicating the presence of human DNA.
Source: XCOM: Enemy Unknown (2012)
Notes
Upon seeing his item on the Alien Base, Dr. Vahlen will ask: "What could they possibly be storing in those tanks?"